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Richard M Sharpe - One of the best experts on this subject based on the ideXlab platform.
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Androgens and the masculinization Programming Window: human-rodent differences.
Biochemical Society transactions, 2020Co-Authors: Richard M SharpeAbstract:Human male reproductive disorders are common and may have a fetal origin - the testicular dysgenesis syndrome (TDS) hypothesis. In rats, experimentally induced TDS disorders result from disruption of fetal androgen production/action specifically in the masculinization Programming Window (MPW). MPW androgen action also programs longer anogenital distance (AGD) in male versus female rats; shorter male AGD is correlated with risk and severity of induced TDS disorders. AGD thus provides a lifelong, calibrated readout of MPW androgen exposure and predicts likelihood of reproductive dysfunction. Pregnant rat exposure to environmental chemicals, notably certain phthalates (e.g. diethyl hexl phthalate, DEHP; dibutyl phthalate, DBP), pesticides or paracetamol, can reduce fetal testis testosterone and AGD and induce TDS disorders, provided exposure includes the MPW. In humans, AGD is longer in males than females and the presumptive MPW is 8-14 weeks' gestation. Some, but not all, epidemiological studies of maternal DEHP (or pesticides) exposure reported shorter AGD in sons, but this occurred at DEHP exposure levels several thousand-fold lower than are effective in rats. In fetal human testis culture/xenografts, DEHP/DBP do not reduce testosterone production, whereas therapeutic paracetamol exposure does. In humans, androgen production in the MPW is controlled differently (human chorionic gonadotrophin-driven) than in rats (paracrine controlled), and other organs (placenta, liver, adrenals) contribute to MPW androgens, essential for normal masculinization, via the 'backdoor pathway'. Consequently, early placental dysfunction, which is affected by maternal lifestyle and diet, and maternal painkiller use, may be more important than environmental chemical exposures in the origin of TDS in humans.
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dibutyl phthalate induced testicular dysgenesis originates after seminiferous cord formation in rats
Scientific Reports, 2017Co-Authors: Sander Van Den Driesche, Sheila Macpherson, N L M Lara, Luiz R Franca, Richard M SharpeAbstract:Administration of dibutyl phthalate (DBP) to pregnant rats causes reproductive disorders in male offspring, resulting from suppression of intratesticular testosterone, and is used as a model for human testicular dysgenesis syndrome (TDS). DBP exposure in pregnancy induces focal dysgenetic areas in fetal testes that appear between e19.5–e21.5, manifesting as focal aggregation of Leydig cells and ectopic Sertoli cells (SC). Our aim was to identify the origins of the ectopic SC. Time-mated female rats were administered 750 mg/kg/day DBP in three different time Windows: full Window (FW; e13.5–e20.5), masculinisation Programming Window (MPW; e15.5–e18.5), late Window (LW; e19.5–e20.5). We show that DBP-MPW treatment produces more extensive and severe dysgenetic areas, with more ectopic SC and germ cells (GC) than DBP-FW treatment; DBP-LW induces no dysgenesis. Our findings demonstrate that ectopic SC do not differentiate de novo, but result from rupture of normally formed seminiferous cords beyond e20.5. The more severe testis dysgenesis in DBP-MPW animals may result from the presence of basally migrating GC and a weakened basal lamina, whereas GC migration was minimal in DBP-FW animals. Our findings provide the first evidence for how testicular dysgenesis can result after normal testis differentiation/development and may be relevant to understanding TDS in human patients.
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dbp treatment during the masculinization Programming Window but not right after it causes break up of seminiferous cords and formation of dysgenetic areas in rats
Animal reproduction, 2017Co-Authors: N L M Lara, Sheila Macpherson, S Van Den Driesche, Luiz R Franca, Richard M SharpeAbstract:Reproductive disorders are extremely common nowadays and some studies show that their incidence may be increasing in the last decades. These disorders include cryptorchidism and hypospadias in newborns and low sperm counts, testis germ cell cancer and hypogonadism in young adult males. These disorders are hypothesized to comprise a Testicular Dysgenesis Syndrome (TDS) in which environmental and lifestyle factors are clearly implicated as potential causes. Although the TDS disorders manifest in different life stages (at birth or young adulthood), there is strong evidence showing that they may have a common origin in fetal life, pointing to the importance of mother’s lifestyle during pregnancy. As male reproductive development is a hormone dependent process, changes in the hormonal balance during fetal life, especially deficiency in androgen production and action during the masculinization Programming Window (MPW), can be related to these disorders. The MPW is thought to occur between 8 and 14 weeks in humans and from e15.5 to e18.5 in rats, a time period that is just after testis differentiation and seminiferous cord formation but before the differentiation of the reproductive tract which is highly dependent on androgens. Gestational exposure of pregnant rats to certain phthalate esters (such as dibutyl phthalate, DBP, which is a common environmental chemical) results in reproductive abnormalities in the male offspring that are very similar to TDS in humans, making this an excellent animal model for studying the fetal origins of human TDS. DBP treatment induces focal dysgenetic areas, which appear between e19.5-e21.5 and manifest as focal aggregation of Leydig cells and presence of ectopic Sertoli cells (SC), even when DBP treatment is initiated (e15.5) after completion of normal SC differentiation and seminiferous cord formation (e13.5-e14.5). There are some unexplained features about these ectopic SC: (1) they do not appear until beyond e19.5 (after cessation of DBP treatment); (2) DBP treatment during the period (e19.5-e21.5) when ectopic SC do appear, rather than during the MPW, fails to induce ectopic SC; (3) unlike normally differentiated SC, the ectopic SC do not form/initiate seminiferous cord formation during fetal life, but only later after birth. Our hypothesis is that the ectopic SC originate from breakdown of already formed seminiferous cords. To address this, time-mated female Wistar rats were treated daily with 750mg/kg/day of DBP in three different Windows: full Window (FW, e13.5-e20.5); masculinization Programming Window (MPW, e15.5-e18.5) or late Window (LW, e19.5-e20.5). Fetal testis sections from the offspring were evaluated at several fetal ages, using triple immunofluorescence and stereology (n=6-12 per age/group). The results show that DBP treatment during the MPW produces more frequent and extensive dysgenetic areas, containing ectopic SC and germ cells (GC), while the LW treatment does not result in any dysgenetic areas. Additionally, the DBP treatment causes clustering of GC in the centre of the cords, especially in the FW and LW groups, while in the MPW group many GC still migrate to the basal lamina, as expected in normal testis development. The intensity of expression of smooth muscle actin, calponin and myosin in peritubular myoid cells at e21.5 in DBP exposed rats (MPW and FW) is reduced, suggesting an impaired basement membrane in these cords. Furthermore, we observed cords breaking up at e20.5 in the MPW group, releasing SC and GC to the interstitial compartment; we presume that this event gives rise to the focal dysgenetic areas observed in the FW and MPW DBP-treated testis. The mechanism for this still need to be investigated, and it might give us better understanding about how dysgenesis arises in human cases of TDS. Also, we show for the first time that a disruption can be induced after the testis is completely formed, and reinforced the critical importance of the MPW in this process.
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prostaglandins masculinization and its disorders effects of fetal exposure of the rat to the cyclooxygenase inhibitor indomethacin
PLOS ONE, 2013Co-Authors: Afshan Dean, William Mungall, Chris Mckinnell, Richard M SharpeAbstract:Recent studies have established that masculinization of the male reproductive tract is programmed by androgens in a critical fetal ‘masculinization Programming Window’ (MPW). What is peculiar to androgen action during this period is, however, unknown. Studies from 20 years ago in mice implicated prostaglandin (PG)-mediation of androgen-induced masculinization, but this has never been followed up. We therefore investigated if PGs might mediate androgen effects in the MPW by exposing pregnant rats to indomethacin (which blocks PG production by inhibiting cyclooxygenase activity) during this period and then examining if androgen production or action (masculinization) was affected. Pregnant rats were treated with indomethacin (0.8 mg/kg/day; e15.5–e18.5) to encompass the MPW. Indomethacin exposure decreased fetal bodyweight (e21.5), testis weight (e21.5) and testicular PGE2 (e17.5, e21.5), but had no effect on intratesticular testosterone (ITT; e17.5) or anogenital index (AGI; e21.5). Postnatally, AGI, testis weight and blood testosterone were unaffected by indomethacin exposure and no cryptorchidism or hypospadias occurred. Penis length was normal in indomethacin-exposed animals at Pnd25 but was reduced by 26% (p<0.001) in adulthood, an effect that is unexplained. Our results demonstrate that indomethacin can effectively decrease intra-testicular PGE2 level. However, the resulting male phenotype does not support a role for PGs in mediating androgen-induced masculinization during the MPW in rats. The contrast with previous mouse studies is unexplained but may reflect a species difference.
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anogenital distance or digit length ratio as measures of fetal androgen exposure relationship to male reproductive development and its disorders
The Journal of Clinical Endocrinology and Metabolism, 2013Co-Authors: Afshan Dean, Richard M SharpeAbstract:Context: Male reproductive disorders evident at birth or in young adulthood are remarkably common. They are hypothesized to comprise a testicular dysgenesis syndrome (TDS), with a fetal origin involving mild androgen deficiency. Evidence Acquisition: Testing this hypothesis requires “seeing back in time.” Two ways have been proposed: measurement of anogenital distance (AGD), or measurement of the 2:4 digit length ratio. This review assesses the evidence that they reflect fetal androgen exposure and might be used to provide insight into the origin of TDS disorders. Evidence Synthesis: Supporting evidence for AGD derives from rat experimental studies that identified a fetal masculinization Programming Window, within which androgen action determines adult reproductive organ size, TDS disorders, and AGD. In humans, AGD is positively correlated to testis size, sperm count/fertility, penis length, and T levels, consistent with rat experimental data. The 2:4 digit ratio also shows associations with these paramet...
Hayley M Scott - One of the best experts on this subject based on the ideXlab platform.
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proposed role for coup tfii in regulating fetal leydig cell steroidogenesis perturbation of which leads to masculinization disorders in rodents
PLOS ONE, 2012Co-Authors: Sander Van Den Driesche, Hayley M Scott, Sharon L Eddie, Amanda J Drake, Marion Walker, Rod T Mitchell, Chris Mckinnell, Lee B Smith, Jonathan R. Seckl, Richard A AndersonAbstract:Reproductive disorders that are common/increasing in prevalence in human males may arise because of deficient androgen production/action during a fetal ‘masculinization Programming Window’. We identify a potentially important role for Chicken Ovalbumin Upstream Promoter-Transcription Factor II (COUP-TFII) in Leydig cell (LC) steroidogenesis that may partly explain this. In rats, fetal LC size and intratesticular testosterone (ITT) increased ∼3-fold between e15.5-e21.5 which associated with a progressive decrease in the percentage of LC expressing COUP-TFII. Exposure of fetuses to dibutyl phthalate (DBP), which induces masculinization disorders, dose-dependently prevented the age-related decrease in LC COUP-TFII expression and the normal increases in LC size and ITT. We show that nuclear COUP-TFII expression in fetal rat LC relates inversely to LC expression of steroidogenic factor-1 (SF-1)-dependent genes (StAR, Cyp11a1, Cyp17a1) with overlapping binding sites for SF-1 and COUP-TFII in their promoter regions, but does not affect an SF-1 dependent LC gene (3β-HSD) without overlapping sites. We also show that once COUP-TFII expression in LC has switched off, it is re-induced by DBP exposure, coincident with suppression of ITT. Furthermore, other treatments that reduce fetal ITT in rats (dexamethasone, diethylstilbestrol (DES)) also maintain/induce LC nuclear expression of COUP-TFII. In contrast to rats, in mice DBP neither causes persistence of fetal LC COUP-TFII nor reduces ITT, whereas DES-exposure of mice maintains COUP-TFII expression in fetal LC and decreases ITT, as in rats. These findings suggest that lifting of repression by COUP-TFII may be an important mechanism that promotes increased testosterone production by fetal LC to drive masculinization. As we also show an age-related decline in expression of COUP-TFII in human fetal LC, this mechanism may also be functional in humans, and its susceptibility to disruption by environmental chemicals, stress and pregnancy hormones could explain the origin of some human male reproductive disorders.
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Origin of Testicular Dysgenesis Syndrome Disorders in the Masculinization Programming Window: Relevance to Final Testis Size (=Sperm Production)
Research and Perspectives in Endocrine Interactions, 2011Co-Authors: Richard M Sharpe, Hayley M Scott, Amanda J Drake, Sarah Auharek, Luiz Renato De Franca, Sander Van Den DriescheAbstract:Testicular dysgenesis syndrome (TDS) disorders are common and/or increasing in incidence in human males, implicating lifestyle/environmental causes. Our studies in rats suggest that TDS disorders originate in fetal life because of deficient testosterone production by the fetal testis within a specific masculinization Programming Window (MPW). Administration of dibutyl phthalate (DBP) to pregnant rats suppresses testosterone levels in the fetal testis more dramatically after the MPW than during the MPW, but only suppression in the MPW affects anogenital distance (AGD), confirming that this simple measure provides a life-long readout of androgen action just within the MPW. Using maternal treatments (DBP, linuron, prochloraz, alone or in combination) that can impair testosterone production by the fetal testis, we show that suppression of androgen action within the MPW, as inferred from AGD, is highly correlated (P < 0.0001) with testis size at e21.5 (when Sertoli cells are still proliferating), at postnatal day 25 (early puberty, when final Sertoli cell number has been determined) and in adulthood (when it equates to the level of sperm production). As a similar correlation was found between AGD and final Sertoli cell number, effects on this parameter probably explain the AGD:testis size correlation. Low sperm count is the commonest TDS disorder, affecting ~20% of young men. Emerging evidence suggests it may originate in fetal life in the MPW, consistent with the present rat studies.
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androgen action in the masculinization Programming Window and development of male reproductive organs
International Journal of Andrology, 2010Co-Authors: Donald Macleod, Hayley M Scott, Michelle Welsh, Mark Fisken, Amanda J Drake, Richard M Sharpe, Gary R Hutchison, Sander Van Den DriescheAbstract:We have shown previously that deficient androgen action within a masculinization Programming Window (MPW; e15.5-e18.5 in rats) is important in the origin of male reproductive disorders and in Programming male reproductive organ size, but that androgen action postnatally may be important to achieve this size. To further investigate importance of the MPW, we used two rat models, in which foetal androgen production or action was impaired during the MPW by exposing in utero to either di(n-butyl) phthalate (DBP) or to flutamide. Reduced anogenital distance (AGD) was used as a monitor of androgen production/action during the MPW. Offspring were evaluated in early puberty (Pnd25) to establish if reproductive organ size was altered. The testes, penis, ventral prostate (VP) and seminal vesicles (SV) were weighed and penis length measured. Both DBP and flutamide exposure in the MPW significantly reduced penis, VP and SV size along with AGD at Pnd25; AGD and organ size were highly correlated. In DBP-, but not flutamide-, exposed animals, testis weight was also reduced and correlated with AGD. Intratesticular testosterone was also measured in control and DBP-exposed males during (e17.5) or after (e21.5) the MPW and related to AGD at e21.5. To evaluate the importance of postnatal androgen action in reproductive organ growth, the effect of combinations of prenatal and postnatal maternal treatments on AGD and penis size at Pnd25 was evaluated. In prenatally DBP-exposed animals, further postnatal exposure to either DBP or flutamide significantly reduced AGD and penis size in comparison with prenatal DBP exposure alone. In comparison, rats exposed postnatally to testosterone propionate after prenatal vehicle-exposure showed considerable increase in these parameters vs. controls. In conclusion, we show that the size of all male reproductive organs is programmed by androgen exposure in the MPW, but that growth towards this size is dependent on androgen action postnatally.
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steroidogenesis in the fetal testis and its susceptibility to disruption by exogenous compounds
Endocrine Reviews, 2009Co-Authors: Hayley M Scott, Ian J Mason, Richard M SharpeAbstract:Masculinization depends on adequate production of testosterone by the fetal testis within a specific “masculinization Programming Window.” Disorders resulting from subtle deficiencies in this process are common in humans, and environmental exposures/lifestyle could contribute causally because common therapeutic and environmental compounds can affect steroidogenesis. This evidence derives mainly from rodent studies, but because there are major species differences in regulation of steroidogenesis in the fetal testis, this may not always be a guide to potential effects in the human. In addition to direct study of the effects of compounds on steroidogenesis, information also derives from study of masculinization disorders that result from mutations in genes in pathways regulating steroidogenesis. This review addresses this issue by critically reviewing the comparative timing of production and regulation of steroidogenesis in the fetal testis of humans and of rodents and its susceptibility to disruption; where...
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steroidogenesis in the fetal testis and its susceptibility to disruption by exogenous compounds
Endocrine Reviews, 2009Co-Authors: Hayley M Scott, Ian J Mason, Richard M SharpeAbstract:Masculinization depends on adequate production of testosterone by the fetal testis within a specific "masculinization Programming Window." Disorders resulting from subtle deficiencies in this process are common in humans, and environmental exposures/lifestyle could contribute causally because common therapeutic and environmental compounds can affect steroidogenesis. This evidence derives mainly from rodent studies, but because there are major species differences in regulation of steroidogenesis in the fetal testis, this may not always be a guide to potential effects in the human. In addition to direct study of the effects of compounds on steroidogenesis, information also derives from study of masculinization disorders that result from mutations in genes in pathways regulating steroidogenesis. This review addresses this issue by critically reviewing the comparative timing of production and regulation of steroidogenesis in the fetal testis of humans and of rodents and its susceptibility to disruption; where there is limited information for the fetus, evidence from effects on steroidogenesis in the adult testis is considered. There are a number of fundamental regulatory differences between the human and rodent fetal testis, most notably in the importance of paracrine vs. endocrine drives during masculinization such that inactivating LH receptor mutations block masculinization in humans but not in rodents. Other large differences involve the steroidogenic response to estrogens and GnRH analogs and possibly phthalates, whereas for other compounds there may be differences in sensitivity to disruption (ketoconazole). This comparison identifies steroidogenic targets that are either vulnerable (mitochondrial cholesterol transport, CYP11A, CYP17) or not (cholesterol uptake) to chemical interference.
Amanda J Drake - One of the best experts on this subject based on the ideXlab platform.
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proposed role for coup tfii in regulating fetal leydig cell steroidogenesis perturbation of which leads to masculinization disorders in rodents
PLOS ONE, 2012Co-Authors: Sander Van Den Driesche, Hayley M Scott, Sharon L Eddie, Amanda J Drake, Marion Walker, Rod T Mitchell, Chris Mckinnell, Lee B Smith, Jonathan R. Seckl, Richard A AndersonAbstract:Reproductive disorders that are common/increasing in prevalence in human males may arise because of deficient androgen production/action during a fetal ‘masculinization Programming Window’. We identify a potentially important role for Chicken Ovalbumin Upstream Promoter-Transcription Factor II (COUP-TFII) in Leydig cell (LC) steroidogenesis that may partly explain this. In rats, fetal LC size and intratesticular testosterone (ITT) increased ∼3-fold between e15.5-e21.5 which associated with a progressive decrease in the percentage of LC expressing COUP-TFII. Exposure of fetuses to dibutyl phthalate (DBP), which induces masculinization disorders, dose-dependently prevented the age-related decrease in LC COUP-TFII expression and the normal increases in LC size and ITT. We show that nuclear COUP-TFII expression in fetal rat LC relates inversely to LC expression of steroidogenic factor-1 (SF-1)-dependent genes (StAR, Cyp11a1, Cyp17a1) with overlapping binding sites for SF-1 and COUP-TFII in their promoter regions, but does not affect an SF-1 dependent LC gene (3β-HSD) without overlapping sites. We also show that once COUP-TFII expression in LC has switched off, it is re-induced by DBP exposure, coincident with suppression of ITT. Furthermore, other treatments that reduce fetal ITT in rats (dexamethasone, diethylstilbestrol (DES)) also maintain/induce LC nuclear expression of COUP-TFII. In contrast to rats, in mice DBP neither causes persistence of fetal LC COUP-TFII nor reduces ITT, whereas DES-exposure of mice maintains COUP-TFII expression in fetal LC and decreases ITT, as in rats. These findings suggest that lifting of repression by COUP-TFII may be an important mechanism that promotes increased testosterone production by fetal LC to drive masculinization. As we also show an age-related decline in expression of COUP-TFII in human fetal LC, this mechanism may also be functional in humans, and its susceptibility to disruption by environmental chemicals, stress and pregnancy hormones could explain the origin of some human male reproductive disorders.
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inter relationship between testicular dysgenesis and leydig cell function in the masculinization Programming Window in the rat
PLOS ONE, 2012Co-Authors: Sander Van Den Driesche, Amanda J Drake, Petros Kolovos, Sophie Platts, Richard M SharpeAbstract:The testicular dysgenesis syndrome (TDS) hypothesis proposes that maldevelopment of the testis, irrespective of cause, leads to malfunction of the somatic (Leydig, Sertoli) cells and consequent downstream TDS disorders. Studies in rats exposed in utero to di(n-butyl) phthalate (DBP) have strongly supported the TDS concept, but so far no direct evidence has been produced that links dysgenesis per se to somatic cell dysfunction, in particular to androgen production/action during the ‘masculinization Programming Window’ (MPW; e15.5–e18.5). Normal reproductive tract development and anogenital distance (AGD) are programmed within the MPW, and TDS disorders arise because of deficiencies in this Programming. However, DBP-induced focal testicular dysgenesis (Leydig cell aggregation, ectopic Sertoli cells, malformed seminiferous cords) is not evident until after the MPW. Therefore, we used AGD as a read-out of androgen exposure in the MPW, and investigated if this measure was related to objectively quantified dysgenesis (Leydig cell aggregation) at e21.5 in male fetuses exposed to vehicle, DBP (500 or 750 mg/kg/day) or the synthetic glucocorticoid dexamethasone (Dex; alone or plus DBP-500) from e15.5–e18.5 (MPW), e13.5–e20.5 or e19.5–e20.5 (late Window). Dysgenesis was found only in animals exposed to DBP during the MPW, and was negatively correlated (R2 = −0.5) with AGD at e21.5 and at postnatal day 8, irrespective of treatment period. Dysgenesis was also negatively correlated (R2 = –0.5) with intratesticular testosterone (ITT) at e21.5, but only when treatments in short Windows (MPW, late Window) were excluded; the same was true for correlation between AGD and ITT. We conclude that AGD, reflecting Leydig cell function solely within the MPW, is strongly related to focal dysgenesis. Our results point to this occurring because of a common early mechanism, targeted by DBP that determines both dysgenesis and early (during the MPW) fetal Leydig cell dysfunction. The findings provide strong validation of the TDS hypothesis.
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Origin of Testicular Dysgenesis Syndrome Disorders in the Masculinization Programming Window: Relevance to Final Testis Size (=Sperm Production)
Research and Perspectives in Endocrine Interactions, 2011Co-Authors: Richard M Sharpe, Hayley M Scott, Amanda J Drake, Sarah Auharek, Luiz Renato De Franca, Sander Van Den DriescheAbstract:Testicular dysgenesis syndrome (TDS) disorders are common and/or increasing in incidence in human males, implicating lifestyle/environmental causes. Our studies in rats suggest that TDS disorders originate in fetal life because of deficient testosterone production by the fetal testis within a specific masculinization Programming Window (MPW). Administration of dibutyl phthalate (DBP) to pregnant rats suppresses testosterone levels in the fetal testis more dramatically after the MPW than during the MPW, but only suppression in the MPW affects anogenital distance (AGD), confirming that this simple measure provides a life-long readout of androgen action just within the MPW. Using maternal treatments (DBP, linuron, prochloraz, alone or in combination) that can impair testosterone production by the fetal testis, we show that suppression of androgen action within the MPW, as inferred from AGD, is highly correlated (P < 0.0001) with testis size at e21.5 (when Sertoli cells are still proliferating), at postnatal day 25 (early puberty, when final Sertoli cell number has been determined) and in adulthood (when it equates to the level of sperm production). As a similar correlation was found between AGD and final Sertoli cell number, effects on this parameter probably explain the AGD:testis size correlation. Low sperm count is the commonest TDS disorder, affecting ~20% of young men. Emerging evidence suggests it may originate in fetal life in the MPW, consistent with the present rat studies.
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androgen action in the masculinization Programming Window and development of male reproductive organs
International Journal of Andrology, 2010Co-Authors: Donald Macleod, Hayley M Scott, Michelle Welsh, Mark Fisken, Amanda J Drake, Richard M Sharpe, Gary R Hutchison, Sander Van Den DriescheAbstract:We have shown previously that deficient androgen action within a masculinization Programming Window (MPW; e15.5-e18.5 in rats) is important in the origin of male reproductive disorders and in Programming male reproductive organ size, but that androgen action postnatally may be important to achieve this size. To further investigate importance of the MPW, we used two rat models, in which foetal androgen production or action was impaired during the MPW by exposing in utero to either di(n-butyl) phthalate (DBP) or to flutamide. Reduced anogenital distance (AGD) was used as a monitor of androgen production/action during the MPW. Offspring were evaluated in early puberty (Pnd25) to establish if reproductive organ size was altered. The testes, penis, ventral prostate (VP) and seminal vesicles (SV) were weighed and penis length measured. Both DBP and flutamide exposure in the MPW significantly reduced penis, VP and SV size along with AGD at Pnd25; AGD and organ size were highly correlated. In DBP-, but not flutamide-, exposed animals, testis weight was also reduced and correlated with AGD. Intratesticular testosterone was also measured in control and DBP-exposed males during (e17.5) or after (e21.5) the MPW and related to AGD at e21.5. To evaluate the importance of postnatal androgen action in reproductive organ growth, the effect of combinations of prenatal and postnatal maternal treatments on AGD and penis size at Pnd25 was evaluated. In prenatally DBP-exposed animals, further postnatal exposure to either DBP or flutamide significantly reduced AGD and penis size in comparison with prenatal DBP exposure alone. In comparison, rats exposed postnatally to testosterone propionate after prenatal vehicle-exposure showed considerable increase in these parameters vs. controls. In conclusion, we show that the size of all male reproductive organs is programmed by androgen exposure in the MPW, but that growth towards this size is dependent on androgen action postnatally.
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relationship between androgen action in the male Programming Window fetal sertoli cell number and adult testis size in the rat
Endocrinology, 2008Co-Authors: Hayley M Scott, Amanda J Drake, Chris Mckinnell, Gary R Hutchison, Matthew S Jobling, Richard M SharpeAbstract:Fetal androgen action is an important determinant of Sertoli cell (SC) number at birth. Androgens "program" reproductive tract development in rats between embryonic d (e) 15.5 and e17.5 ("male Programming Window"), and this is reflected for life by anogenital distance (AGD). We investigated if androgen regulation of SC number/proliferation was also programmed by androgens in this Window. Pregnant rats were treated in various fetal time Windows with vehicle (control) or 500 mg/kg.d di(n-butyl) phthalate (DBP), which suppresses fetal intratesticular testosterone (ITT). ITT and SC number/proliferation index were determined at e17.5 or e21.5; AGD was also determined at e21.5. In controls, SC number increased 11-fold and ITT by 10-fold from e17.5-e21.5. In animals exposed daily to DBP from e13.5, SC number was reduced by approximately 50% at e21.5, but increased 6-fold, as did ITT, from e17.5-e21.5; DBP had no effect on ITT at e15.5, reduced ITT by 50% at e17.5, and by more than 75% at e19.5-21.5. DBP exposure just in the male Programming Window did not alter SC number at e17.5 or 21.5 but reduced AGD. DBP treatment beyond e19.5 caused major reductions in SC number/proliferation index and ITT at e21.5. Only DBP treatments that included the male Programming Window led to reduced AGD at e21.5, but SC number was clearly not programmed in this Window. Nevertheless, testis weight correlated highly (P<0.001) with AGD at e21.5, and postnatal d 25 and 90 in animals exposed in utero to vehicle or DBP (e13.5-e21.5). Thus, AGD may predict adult testis size but probably not through a direct relationship with SC number.
Chris Mckinnell - One of the best experts on this subject based on the ideXlab platform.
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experimentally induced testicular dysgenesis syndrome originates in the masculinization Programming Window
JCI insight, 2017Co-Authors: Sander Van Den Driesche, Karen R Kilcoyne, Ida Wagner, Diane Rebourcet, Ashley K Boyle, Rod T Mitchell, Chris Mckinnell, Sheila Macpherson, Roland Donat, Chitranjan J ShuklaAbstract:The testicular dysgenesis syndrome (TDS) hypothesis, which proposes that common reproductive disorders of newborn and adult human males may have a common fetal origin, is largely untested. We tested this hypothesis using a rat model involving gestational exposure to dibutyl phthalate (DBP), which suppresses testosterone production by the fetal testis. We evaluated if induction of TDS via testosterone suppression is restricted to the “masculinization Programming Window” (MPW), as indicated by reduction in anogenital distance (AGD). We show that DBP suppresses fetal testosterone equally during and after the MPW, but only DBP exposure in the MPW causes reduced AGD, focal testicular dysgenesis, and TDS disorders (cryptorchidism, hypospadias, reduced adult testis size, and compensated adult Leydig cell failure). Focal testicular dysgenesis, reduced size of adult male reproductive organs, and TDS disorders and their severity were all strongly associated with reduced AGD. We related our findings to human TDS cases by demonstrating similar focal dysgenetic changes in testes of men with preinvasive germ cell neoplasia (GCNIS) and in testes of DBP-MPW animals. If our results are translatable to humans, they suggest that identification of potential causes of human TDS disorders should focus on exposures during a human MPW equivalent, especially if negatively associated with offspring AGD.
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prostaglandins masculinization and its disorders effects of fetal exposure of the rat to the cyclooxygenase inhibitor indomethacin
PLOS ONE, 2013Co-Authors: Afshan Dean, William Mungall, Chris Mckinnell, Richard M SharpeAbstract:Recent studies have established that masculinization of the male reproductive tract is programmed by androgens in a critical fetal ‘masculinization Programming Window’ (MPW). What is peculiar to androgen action during this period is, however, unknown. Studies from 20 years ago in mice implicated prostaglandin (PG)-mediation of androgen-induced masculinization, but this has never been followed up. We therefore investigated if PGs might mediate androgen effects in the MPW by exposing pregnant rats to indomethacin (which blocks PG production by inhibiting cyclooxygenase activity) during this period and then examining if androgen production or action (masculinization) was affected. Pregnant rats were treated with indomethacin (0.8 mg/kg/day; e15.5–e18.5) to encompass the MPW. Indomethacin exposure decreased fetal bodyweight (e21.5), testis weight (e21.5) and testicular PGE2 (e17.5, e21.5), but had no effect on intratesticular testosterone (ITT; e17.5) or anogenital index (AGI; e21.5). Postnatally, AGI, testis weight and blood testosterone were unaffected by indomethacin exposure and no cryptorchidism or hypospadias occurred. Penis length was normal in indomethacin-exposed animals at Pnd25 but was reduced by 26% (p<0.001) in adulthood, an effect that is unexplained. Our results demonstrate that indomethacin can effectively decrease intra-testicular PGE2 level. However, the resulting male phenotype does not support a role for PGs in mediating androgen-induced masculinization during the MPW in rats. The contrast with previous mouse studies is unexplained but may reflect a species difference.
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proposed role for coup tfii in regulating fetal leydig cell steroidogenesis perturbation of which leads to masculinization disorders in rodents
PLOS ONE, 2012Co-Authors: Sander Van Den Driesche, Hayley M Scott, Sharon L Eddie, Amanda J Drake, Marion Walker, Rod T Mitchell, Chris Mckinnell, Lee B Smith, Jonathan R. Seckl, Richard A AndersonAbstract:Reproductive disorders that are common/increasing in prevalence in human males may arise because of deficient androgen production/action during a fetal ‘masculinization Programming Window’. We identify a potentially important role for Chicken Ovalbumin Upstream Promoter-Transcription Factor II (COUP-TFII) in Leydig cell (LC) steroidogenesis that may partly explain this. In rats, fetal LC size and intratesticular testosterone (ITT) increased ∼3-fold between e15.5-e21.5 which associated with a progressive decrease in the percentage of LC expressing COUP-TFII. Exposure of fetuses to dibutyl phthalate (DBP), which induces masculinization disorders, dose-dependently prevented the age-related decrease in LC COUP-TFII expression and the normal increases in LC size and ITT. We show that nuclear COUP-TFII expression in fetal rat LC relates inversely to LC expression of steroidogenic factor-1 (SF-1)-dependent genes (StAR, Cyp11a1, Cyp17a1) with overlapping binding sites for SF-1 and COUP-TFII in their promoter regions, but does not affect an SF-1 dependent LC gene (3β-HSD) without overlapping sites. We also show that once COUP-TFII expression in LC has switched off, it is re-induced by DBP exposure, coincident with suppression of ITT. Furthermore, other treatments that reduce fetal ITT in rats (dexamethasone, diethylstilbestrol (DES)) also maintain/induce LC nuclear expression of COUP-TFII. In contrast to rats, in mice DBP neither causes persistence of fetal LC COUP-TFII nor reduces ITT, whereas DES-exposure of mice maintains COUP-TFII expression in fetal LC and decreases ITT, as in rats. These findings suggest that lifting of repression by COUP-TFII may be an important mechanism that promotes increased testosterone production by fetal LC to drive masculinization. As we also show an age-related decline in expression of COUP-TFII in human fetal LC, this mechanism may also be functional in humans, and its susceptibility to disruption by environmental chemicals, stress and pregnancy hormones could explain the origin of some human male reproductive disorders.
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Speaker abstracts: S01: New insights into fetal masculinisation disorders and the implications for endocrine disruptor effects
Experimental and Toxicologic Pathology, 2009Co-Authors: Richard M Sharpe, Hayley M Scott, Chris Mckinnell, Gary R Hutchison, Sander Van Den Driesche, David Macleod, M. S. Jobling, Marion F Walker, Michelle WelshAbstract:Becoming a male is ultimately determined by androgen-induced masculinisation. Disorders of this, resulting in hypospadias (abnormal penis development) or cryptorchidism (undescended testes), are common disorders in humans. Together with adult onset disorders (low sperm counts, testis germ cell cancer) hypospadias and cryptorchidism may constitute a testicular dysgenesis syndrome (TDS) in humans, with a proposed common fetal origin that may involve deficiencies in androgen production or action. As animal evidence has shown that anti-androgenic endocrine disruptors (EDs) can induce TDS-like effects, concern has grown regarding their potential involvement in human TDS disorders. We have developed a rat model of TDS, in which we have begun to dissect the fetal mechanisms that underlie TDS disorders. Using another rat model in which androgen action is blocked by the anti-androgen flutamide, we have recently identified a ‘male Programming Window’, which available evidence suggests occurs also in the human fetus (between ∼8 and 12 week's gestation). Androgens must act within this Programming Window to set up later correct development of the reproductive tract and genitalia. Surprisingly, androgen-driven (abnormal) masculinisation of females is confined to the same Programming Window as for normal males. Blocking androgen action only within the Programming Window induces hypospadias and cryptorchidism and alters penile length in males; these all correlate with reduction in anogenital distance (AGD), which provides a non-invasive, lifelong read-out of androgen exposure in the Programming Window (but not later in gestation). As AGD is measurable in human newborns/neonates, it may predict adult onset TDS disorders and provide clinically important insights into reproductive tract masculinisation and its disorders. With this new understanding we have also begun to explore the role and timescale of effects of androgens in regulation of penile development and size. We show in the rat, that AGD predicts fetal and adult testis size (and thus sperm production), but the mechanism underlying this is unknown as it is not explained by effects on Sertoli cell number, as androgen regulation of Sertoli cell proliferation extends beyond the ‘male Programming Window’ (when AGD is determined); this relationship is of potential importance in the context of fetal origins of low sperm counts in humans. These findings strongly support the view that deficient fetal androgen action is a key feature of TDS. We postulate that delayed onset of fetal testosterone production may also be important in TDS. These new findings have considerable implications with regard to the time-Window of susceptibility of the fetal male to disruption by EDs.
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relationship between androgen action in the male Programming Window fetal sertoli cell number and adult testis size in the rat
Endocrinology, 2008Co-Authors: Hayley M Scott, Amanda J Drake, Chris Mckinnell, Gary R Hutchison, Matthew S Jobling, Richard M SharpeAbstract:Fetal androgen action is an important determinant of Sertoli cell (SC) number at birth. Androgens "program" reproductive tract development in rats between embryonic d (e) 15.5 and e17.5 ("male Programming Window"), and this is reflected for life by anogenital distance (AGD). We investigated if androgen regulation of SC number/proliferation was also programmed by androgens in this Window. Pregnant rats were treated in various fetal time Windows with vehicle (control) or 500 mg/kg.d di(n-butyl) phthalate (DBP), which suppresses fetal intratesticular testosterone (ITT). ITT and SC number/proliferation index were determined at e17.5 or e21.5; AGD was also determined at e21.5. In controls, SC number increased 11-fold and ITT by 10-fold from e17.5-e21.5. In animals exposed daily to DBP from e13.5, SC number was reduced by approximately 50% at e21.5, but increased 6-fold, as did ITT, from e17.5-e21.5; DBP had no effect on ITT at e15.5, reduced ITT by 50% at e17.5, and by more than 75% at e19.5-21.5. DBP exposure just in the male Programming Window did not alter SC number at e17.5 or 21.5 but reduced AGD. DBP treatment beyond e19.5 caused major reductions in SC number/proliferation index and ITT at e21.5. Only DBP treatments that included the male Programming Window led to reduced AGD at e21.5, but SC number was clearly not programmed in this Window. Nevertheless, testis weight correlated highly (P<0.001) with AGD at e21.5, and postnatal d 25 and 90 in animals exposed in utero to vehicle or DBP (e13.5-e21.5). Thus, AGD may predict adult testis size but probably not through a direct relationship with SC number.
Gary R Hutchison - One of the best experts on this subject based on the ideXlab platform.
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androgen action in the masculinization Programming Window and development of male reproductive organs
International Journal of Andrology, 2010Co-Authors: Donald Macleod, Hayley M Scott, Michelle Welsh, Mark Fisken, Amanda J Drake, Richard M Sharpe, Gary R Hutchison, Sander Van Den DriescheAbstract:We have shown previously that deficient androgen action within a masculinization Programming Window (MPW; e15.5-e18.5 in rats) is important in the origin of male reproductive disorders and in Programming male reproductive organ size, but that androgen action postnatally may be important to achieve this size. To further investigate importance of the MPW, we used two rat models, in which foetal androgen production or action was impaired during the MPW by exposing in utero to either di(n-butyl) phthalate (DBP) or to flutamide. Reduced anogenital distance (AGD) was used as a monitor of androgen production/action during the MPW. Offspring were evaluated in early puberty (Pnd25) to establish if reproductive organ size was altered. The testes, penis, ventral prostate (VP) and seminal vesicles (SV) were weighed and penis length measured. Both DBP and flutamide exposure in the MPW significantly reduced penis, VP and SV size along with AGD at Pnd25; AGD and organ size were highly correlated. In DBP-, but not flutamide-, exposed animals, testis weight was also reduced and correlated with AGD. Intratesticular testosterone was also measured in control and DBP-exposed males during (e17.5) or after (e21.5) the MPW and related to AGD at e21.5. To evaluate the importance of postnatal androgen action in reproductive organ growth, the effect of combinations of prenatal and postnatal maternal treatments on AGD and penis size at Pnd25 was evaluated. In prenatally DBP-exposed animals, further postnatal exposure to either DBP or flutamide significantly reduced AGD and penis size in comparison with prenatal DBP exposure alone. In comparison, rats exposed postnatally to testosterone propionate after prenatal vehicle-exposure showed considerable increase in these parameters vs. controls. In conclusion, we show that the size of all male reproductive organs is programmed by androgen exposure in the MPW, but that growth towards this size is dependent on androgen action postnatally.
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Speaker abstracts: S01: New insights into fetal masculinisation disorders and the implications for endocrine disruptor effects
Experimental and Toxicologic Pathology, 2009Co-Authors: Richard M Sharpe, Hayley M Scott, Chris Mckinnell, Gary R Hutchison, Sander Van Den Driesche, David Macleod, M. S. Jobling, Marion F Walker, Michelle WelshAbstract:Becoming a male is ultimately determined by androgen-induced masculinisation. Disorders of this, resulting in hypospadias (abnormal penis development) or cryptorchidism (undescended testes), are common disorders in humans. Together with adult onset disorders (low sperm counts, testis germ cell cancer) hypospadias and cryptorchidism may constitute a testicular dysgenesis syndrome (TDS) in humans, with a proposed common fetal origin that may involve deficiencies in androgen production or action. As animal evidence has shown that anti-androgenic endocrine disruptors (EDs) can induce TDS-like effects, concern has grown regarding their potential involvement in human TDS disorders. We have developed a rat model of TDS, in which we have begun to dissect the fetal mechanisms that underlie TDS disorders. Using another rat model in which androgen action is blocked by the anti-androgen flutamide, we have recently identified a ‘male Programming Window’, which available evidence suggests occurs also in the human fetus (between ∼8 and 12 week's gestation). Androgens must act within this Programming Window to set up later correct development of the reproductive tract and genitalia. Surprisingly, androgen-driven (abnormal) masculinisation of females is confined to the same Programming Window as for normal males. Blocking androgen action only within the Programming Window induces hypospadias and cryptorchidism and alters penile length in males; these all correlate with reduction in anogenital distance (AGD), which provides a non-invasive, lifelong read-out of androgen exposure in the Programming Window (but not later in gestation). As AGD is measurable in human newborns/neonates, it may predict adult onset TDS disorders and provide clinically important insights into reproductive tract masculinisation and its disorders. With this new understanding we have also begun to explore the role and timescale of effects of androgens in regulation of penile development and size. We show in the rat, that AGD predicts fetal and adult testis size (and thus sperm production), but the mechanism underlying this is unknown as it is not explained by effects on Sertoli cell number, as androgen regulation of Sertoli cell proliferation extends beyond the ‘male Programming Window’ (when AGD is determined); this relationship is of potential importance in the context of fetal origins of low sperm counts in humans. These findings strongly support the view that deficient fetal androgen action is a key feature of TDS. We postulate that delayed onset of fetal testosterone production may also be important in TDS. These new findings have considerable implications with regard to the time-Window of susceptibility of the fetal male to disruption by EDs.
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relationship between androgen action in the male Programming Window fetal sertoli cell number and adult testis size in the rat
Endocrinology, 2008Co-Authors: Hayley M Scott, Amanda J Drake, Chris Mckinnell, Gary R Hutchison, Matthew S Jobling, Richard M SharpeAbstract:Fetal androgen action is an important determinant of Sertoli cell (SC) number at birth. Androgens "program" reproductive tract development in rats between embryonic d (e) 15.5 and e17.5 ("male Programming Window"), and this is reflected for life by anogenital distance (AGD). We investigated if androgen regulation of SC number/proliferation was also programmed by androgens in this Window. Pregnant rats were treated in various fetal time Windows with vehicle (control) or 500 mg/kg.d di(n-butyl) phthalate (DBP), which suppresses fetal intratesticular testosterone (ITT). ITT and SC number/proliferation index were determined at e17.5 or e21.5; AGD was also determined at e21.5. In controls, SC number increased 11-fold and ITT by 10-fold from e17.5-e21.5. In animals exposed daily to DBP from e13.5, SC number was reduced by approximately 50% at e21.5, but increased 6-fold, as did ITT, from e17.5-e21.5; DBP had no effect on ITT at e15.5, reduced ITT by 50% at e17.5, and by more than 75% at e19.5-21.5. DBP exposure just in the male Programming Window did not alter SC number at e17.5 or 21.5 but reduced AGD. DBP treatment beyond e19.5 caused major reductions in SC number/proliferation index and ITT at e21.5. Only DBP treatments that included the male Programming Window led to reduced AGD at e21.5, but SC number was clearly not programmed in this Window. Nevertheless, testis weight correlated highly (P<0.001) with AGD at e21.5, and postnatal d 25 and 90 in animals exposed in utero to vehicle or DBP (e13.5-e21.5). Thus, AGD may predict adult testis size but probably not through a direct relationship with SC number.
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Relationship between Androgen Action in the “Male Programming Window,” Fetal Sertoli Cell Number, and Adult Testis Size in the Rat
Endocrinology, 2008Co-Authors: Hayley M Scott, Amanda J Drake, Chris Mckinnell, Gary R Hutchison, Matthew S Jobling, Richard M SharpeAbstract:Fetal androgen action is an important determinant of Sertoli cell (SC) number at birth. Androgens "program" reproductive tract development in rats between embryonic d (e) 15.5 and e17.5 ("male Programming Window"), and this is reflected for life by anogenital distance (AGD). We investigated if androgen regulation of SC number/proliferation was also programmed by androgens in this Window. Pregnant rats were treated in various fetal time Windows with vehicle (control) or 500 mg/kg.d di(n-butyl) phthalate (DBP), which suppresses fetal intratesticular testosterone (ITT). ITT and SC number/proliferation index were determined at e17.5 or e21.5; AGD was also determined at e21.5. In controls, SC number increased 11-fold and ITT by 10-fold from e17.5-e21.5. In animals exposed daily to DBP from e13.5, SC number was reduced by approximately 50% at e21.5, but increased 6-fold, as did ITT, from e17.5-e21.5; DBP had no effect on ITT at e15.5, reduced ITT by 50% at e17.5, and by more than 75% at e19.5-21.5. DBP exposure just in the male Programming Window did not alter SC number at e17.5 or 21.5 but reduced AGD. DBP treatment beyond e19.5 caused major reductions in SC number/proliferation index and ITT at e21.5. Only DBP treatments that included the male Programming Window led to reduced AGD at e21.5, but SC number was clearly not programmed in this Window. Nevertheless, testis weight correlated highly (P
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identification in rats of a Programming Window for reproductive tract masculinization disruption of which leads to hypospadias and cryptorchidism
Journal of Clinical Investigation, 2008Co-Authors: Michelle Welsh, Hayley M Scott, Mark Fisken, Philippa T. K. Saunders, Lee B Smith, Gary R Hutchison, Richard M SharpeAbstract:Becoming a phenotypic male is ultimately determined by androgen-induced masculinization. Disorders of fetal masculinization, resulting in hypospadias or cryptorchidism, are common, but their cause remains unclear. Together with the adult-onset disorders low sperm count and testicular cancer, they can constitute a testicular dysgenesis syndrome (TDS). Although masculinization is well studied, no unifying concept explains normal male reproductive development and its abnormalities, including TDS. We exposed rat fetuses to either anti-androgens or androgens and showed that masculinization of all reproductive tract tissues was programmed by androgen action during a common fetal Programming Window. This preceded morphological differentiation, when androgen action was, surprisingly, unnecessary. Only within the Programming Window did blocking androgen action induce hypospadias and cryptorchidism and altered penile length in male rats, all of which correlated with anogenital distance (AGD). Androgen-driven masculinization of females was also confined to the same Programming Window. This work has identified in rats a common Programming Window in which androgen action is essential for normal reproductive tract masculinization and has highlighted that measuring AGD in neonatal humans could provide a noninvasive method to predict neonatal and adult reproductive disorders. Based on the timings in rats, we believe the Programming Window in humans is likely to be 8–14 weeks of gestation.
