The Experts below are selected from a list of 174 Experts worldwide ranked by ideXlab platform
Allen J Wilcox - One of the best experts on this subject based on the ideXlab platform.
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rescue of the Corpus Luteum in human pregnancy
Biology of Reproduction, 2003Co-Authors: Donna D Baird, Clarice R Weinberg, Robert D Mcconnaughey, Allen J WilcoxAbstract:Rescue of the Corpus Luteum from its programmed senescence maintains progesterone production required for pregnancy. In primates, chorionic gonadotropin produced by the developing conceptus acts as the primary luteotrophic signal. The purpose of this research was to assess Corpus Luteum rescue by examining changes in daily urinary progesterone metabolite levels during the first week after implantation. We determined the variability in progesterone metabolite profiles and evaluated its relationship to early pregnancy loss in 120 naturally conceived human pregnancies, including 43 early pregnancy losses. In other primates, an abrupt increase in the progesterone metabolite occurs at the time of implantation. This pattern occurred in an estimated 45% of the pregnancies in the present study. In the remaining pregnancies, there was a delayed rise (18%), neither a rise or decline (22%), or a decline (15%) during the week after implantation. The estimated rate of early pregnancy loss increased across these categories (from 5% loss with an abrupt rise at implantation to 100% loss with progesterone metabolite decline). Low urinary hCG levels in early pregnancy were significant determinants of a decline in postimplantation progesterone metabolite. However, preimplantation steroid metabolite levels were not significant, suggesting no inherent problem with the Corpus Luteum. Examination of individual progesterone metabolite profiles in relation to hCG profiles also indicated that few losses were caused by Corpus Luteum failure. Delineating the functional importance of an abrupt progesterone rise at the time of implantation may provide new strategies for promoting successful implantation in assisted reproduction.
Takashi Suzuki - One of the best experts on this subject based on the ideXlab platform.
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Localization of Steroidogenesis and Steroid Receptors in Human Corpus Luteum
Seminars in Reproductive Endocrinology, 2008Co-Authors: Hironobu Sasano, Takashi SuzukiAbstract:: In the analysis of the regulation of human Corpus Luteum, it is very important to localize the sites of specific steroid hormone production to obtain a better understanding of luteal function. We have examined expression of steroidogenic enzymes, steroid receptors, and adrenal 4 binding protein (Ad4BP), a transcription factor of steroidogenesis, in Corpus Luteum of normal cycling human ovary. Corpus Luteum can be classified into four different stages from ovulation to complete regression or fibrosis based on these findings: (1) Corpus Luteum, (2) steroid-producing degenerating Corpus Luteum or SPDCL, (3) nonsteroid producing or NSPDCL, and (4) Corpus albicans. Corpus Luteum in the luteal phase is characterized as follows: (a) the expression of P450scc (cholesterol side chain cleavage), 3 beta HSD (hydroxysteroid dehydrogenase), and Ad4BP in almost all the luteinized granulosa and theca cells, consistent with active progesterone biosynthesis; (b) expression of estrogen-producing P450arom (aromatase) in luteinized granulosa cells, indicating active estrogen production and that of P450c17 (17 alpha hydroxylase) in luteinized theca cells, and (c) expression of progesterone receptor (PR) and androgen receptor (AR) in both luteinized granulosa and theca cells. SPDCL correspond to Corpus Luteum undergoing regression or degeneration in the following cycle and are characterized as follows: (a) absence of all the steroidogenic enzymes and Ad4BP in the luteinized granulosa cells, suggestive of hormonally inactive nature of these cells and (b) marked expression of P450scc, 3 beta HSD, P450c17 and Ad4BP in luteinized theca cells. NSPDCL is characterized as the absence of all the steroidogenic enzymes and sporadic expression of Ad4BP in luteinized theca cells. These findings indicate that luteal cells remain even after losing expression of steroidogenic enzymes, consistent with a prolonged process of degeneration or regression of human Corpus Luteum. In Corpus albicans, all the cells were replaced by fibrosis and steroidogenic enzymes; steroid receptors and Ad4BP were not expressed at all. Localization of steroidogenesis in human Corpus Luteum has thus provided new insights into understanding of its biological features.
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angiogenesis in the human Corpus Luteum changes in expression of angiopoietins in the Corpus Luteum throughout the menstrual cycle and in early pregnancy
The Journal of Clinical Endocrinology and Metabolism, 2005Co-Authors: Norihiro Sugino, Aki Sakata, Ichiro Miwa, Hiromi Asada, Toshiaki Taketani, Yoshiaki Yamagata, Takashi Suzuki, Hiroshi TamuraAbstract:Context: Blood vessel stabilization is regulated by angiopoietins and important for angiogenesis in the Corpus Luteum. Objective: To study angiogenesis and blood vessel stabilization in the human Corpus Luteum, changes in expression of angiopoietin (Ang)-1, Ang-2, and their specific receptor, Tie-2, together with the number of blood vessels and pericytes were examined in the Corpus Luteum throughout the menstrual cycle and in early pregnancy. Design: The number of blood vessels and pericytes was determined by immunohistochemistry for CD34 and α-smooth muscle actin, respectively. Ang and Tie-2 expression were examined by immunohistochemistry or RT-PCR. Results: The number of blood vessels increased during the early luteal phase, whereas the number of pericytes was small in the early luteal phase and increased in the midluteal phase, suggesting that angiogenesis is undergoing during the early luteal phase and blood vessels are stabilized in the midluteal phase. Blood vessels and pericytes decreased in numbe...
Joy L Pate - One of the best experts on this subject based on the ideXlab platform.
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Lives in the balance: responsiveness of the Corpus Luteum to uterine and embryonic signals.
Reproduction (Cambridge England) Supplement, 2020Co-Authors: Joy L PateAbstract:: This review focuses on factors that may affect the sensitivity of the Corpus Luteum to uterine prostaglandin F2alpha (PGF2alpha) and embryonic signals. The heterogeneity of the types of cell that are present within the Corpus Luteum results in complex interactions that ensure complete luteal regression in response to PGF2alpha. There is not likely to be a single factor that determines responsiveness. The sensitivity of the Corpus Luteum depends on the proper balance of a variety of factors that are involved in mediating the effects of PGF2alpha. This balance is achieved as the early Corpus Luteum undergoes development, but may also be altered by embryonic factors to rescue the Corpus Luteum during early pregnancy.
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immune cells in the Corpus Luteum friends or foes
Reproduction, 2001Co-Authors: Joy L Pate, Landis P KeyesAbstract:The Corpus Luteum produces progesterone, which is essential for the maintenance of pregnancy. In the absence of a viable embryo, the Corpus Luteum must regress rapidly to allow for development of new ovulatory follicles. In many species, luteal regression is initiated by uterine release of PGF 2α , which inhibits steroidogenesis and may launch a cascade of events leading to the ultimate demise of the tissue. Immune cells, primarily macrophages and T lymphocytes, are present in the Corpus Luteum, particularly at the time of luteolysis. The macrophages are important for ingestion of cellular remnants that result from the death of luteal cells. However, it has also been hypothesized that immune cells are involved directly in the destruction of luteal cells, as well as in the loss of steroidogenesis; this hypothesis is reviewed in the first part of this article. An alternative hypothesis is also presented, namely that immune cells serve to abate an inflammatory response generated by dead and dying luteal cells, in effect, preventing a response that would otherwise damage surrounding ovarian tissues. Finally, the changes in immune cells that accompany maternal recognition of pregnancy and rescue of the Corpus Luteum are discussed briefly. Inhibition of immune cells in the Corpus Luteum during early pregnancy may be due to embryonic or uterine signals, or to maintenance of high progesterone concentrations within the luteal tissue.
G E Mann - One of the best experts on this subject based on the ideXlab platform.
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Corpus Luteum size and plasma progesterone concentration in cows
Animal Reproduction Science, 2009Co-Authors: G E MannAbstract:Abstract It is often assumed that a larger Corpus Luteum will produce more progesterone and generate higher circulating plasma concentrations. The aim of the study was to determine whether the size of the Corpus Luteum does actually determine circulating plasma progesterone concentrations. Data were collated from a number of studies on various aspects of luteal function in non-lactating dairy cows to allow comparisons to be made between Corpus Luteum weight and plasma progesterone concentration across the luteal phase. In these studies oestrous cycles had been synchronised and animals slaughtered on day 5, day 8 or day 16 following oestrus. Both Corpus Luteum weight and plasma progesterone concentration increased between day 5 and day 8. Plasma progesterone concentration but not luteal weight also increased between day 8 and day 16. On day 5 there was a strong relationship between Corpus Luteum weight and plasma progesterone ( R 2 =0.64; P
Donna D Baird - One of the best experts on this subject based on the ideXlab platform.
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rescue of the Corpus Luteum in human pregnancy
Biology of Reproduction, 2003Co-Authors: Donna D Baird, Clarice R Weinberg, Robert D Mcconnaughey, Allen J WilcoxAbstract:Rescue of the Corpus Luteum from its programmed senescence maintains progesterone production required for pregnancy. In primates, chorionic gonadotropin produced by the developing conceptus acts as the primary luteotrophic signal. The purpose of this research was to assess Corpus Luteum rescue by examining changes in daily urinary progesterone metabolite levels during the first week after implantation. We determined the variability in progesterone metabolite profiles and evaluated its relationship to early pregnancy loss in 120 naturally conceived human pregnancies, including 43 early pregnancy losses. In other primates, an abrupt increase in the progesterone metabolite occurs at the time of implantation. This pattern occurred in an estimated 45% of the pregnancies in the present study. In the remaining pregnancies, there was a delayed rise (18%), neither a rise or decline (22%), or a decline (15%) during the week after implantation. The estimated rate of early pregnancy loss increased across these categories (from 5% loss with an abrupt rise at implantation to 100% loss with progesterone metabolite decline). Low urinary hCG levels in early pregnancy were significant determinants of a decline in postimplantation progesterone metabolite. However, preimplantation steroid metabolite levels were not significant, suggesting no inherent problem with the Corpus Luteum. Examination of individual progesterone metabolite profiles in relation to hCG profiles also indicated that few losses were caused by Corpus Luteum failure. Delineating the functional importance of an abrupt progesterone rise at the time of implantation may provide new strategies for promoting successful implantation in assisted reproduction.
