The Experts below are selected from a list of 318 Experts worldwide ranked by ideXlab platform
Takehiko Ogawa - One of the best experts on this subject based on the ideXlab platform.
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Regeneration of Spermatogenesis after testicular cancer chemotherapy.
Urologia Internationalis, 2013Co-Authors: Kotaro Suzuki, Yasushi Yumura, Takehiko Ogawa, Kazuo Saito, Yuzo Kinoshita, Kazumi NoguchiAbstract:Purpose: Azoospermia is a common side effect of chemotherapy. Although most patients restore Spermatogenesis over time, the exact time course has not been well described. We analyzed the recovery of Spermatogenesis in testicular cancer patients following chemotherapy. Patients and Methods: 49 patients, consisting of 45 treated with a bleomycin, etoposide and cisplatin (BEP) regimen and 4 with high-dose chemotherapy, were followed up with occasional semen analyses. The primary endpoint of this study was the confirmation of motile spermatozoa in the patients' semen. Results: Among 45 patients treated with BEP, 44 recovered Spermatogenesis. The recovery of Spermatogenesis was delayed depending on the increase in BEP cycles. In groups of patients who received 1-2, 3 and 4 cycles, the recovery rates of Spermatogenesis within 2 year were 83.3, 80.0 and 66.7%, respectively. In the group with 5-6 cycles of BEP, re-Spermatogenesis was significantly delayed and no patients re-established Spermatogenesis within 2 years. The patients' age and semen parameters before chemotherapy were not useful as predictive factors for the recovery of Spermatogenesis. Conclusion: The recovery of Spermatogenesis was rather fast and was often observed as early as several months after BEP treatment when the number of cycles was
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in vitro production of functional sperm in cultured neonatal mouse testes
Nature, 2011Co-Authors: Takuya Sato, Kumiko Katagiri, Ayako Gohbara, Kimiko Inoue, Narumi Ogonuki, Atsuo Ogura, Yoshinobu Kubota, Takehiko OgawaAbstract:Reproducing the complex process of Spermatogenesis in vitro might lead to the development of new diagnostic and therapeutic techniques for male infertility. Takehiko Ogawa and colleagues have now established in vitro organ culture conditions that can support the production of fertile sperm from spermatogonia of neonatal mice. Spermatids and sperm that were derived in vitro produced healthy and fertile mice. In addition, neonatal testis tissues that were cryopreserved for several months resumed complete Spermatogenesis in vitro on thawing. The organ culture method is simple and, with further refinements, could be applicable to a variety of mammalian species. This work suggests that cryopreservation of the testis tissue of paediatric cancer patients could become a practical way of ensuring future fertility. Reproducing the complex process of Spermatogenesis in vitro might lead to the development of new diagnostic and therapeutic techniques for male infertility. This study establishes in vitro organ culture conditions that can support complete Spermatogenesis in mice. The in-vitro-derived spermatids and sperm produced healthy and fertile mice, and testis tissue fragments used as a starting material for in vitro Spermatogenesis could be cryopreserved for months and then resumed full Spermatogenesis in vitro. Spermatogenesis is one of the most complex and longest processes of sequential cell proliferation and differentiation in the body, taking more than a month from spermatogonial stem cells, through meiosis, to sperm formation1,2. The whole process, therefore, has never been reproduced in vitro in mammals3,4,5, nor in any other species with a very few exceptions in some particular types of fish6,7. Here we show that neonatal mouse testes which contain only gonocytes or primitive spermatogonia as germ cells can produce spermatids and sperm in vitro with serum-free culture media. Spermatogenesis was maintained over 2 months in tissue fragments positioned at the gas–liquid interphase. The obtained spermatids and sperm resulted in healthy and reproductively competent offspring through microinsemination. In addition, neonatal testis tissues were cryopreserved and, after thawing, showed complete Spermatogenesis in vitro. Our organ culture method could be applicable through further refinements to a variety of mammalian species, which will serve as a platform for future clinical application as well as mechanistic understanding of Spermatogenesis.
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xenogeneic Spermatogenesis following transplantation of hamster germ cells to mouse testes
Biology of Reproduction, 1999Co-Authors: Takehiko Ogawa, Ina Dobrinski, Mary R Avarbock, Ralph L BrinsterAbstract:It was recently demonstrated that rat Spermatogenesis can occur in the seminiferous tubules of an immunodeficient recipient mouse after transplantation of testis cells from a donor rat. In the present study, hamster donor testis cells were transplanted to mice to determine whether xenogeneic Spermatogenesis would result. The hamster diverged at least 16 million years ago from the mouse and produces spermatozoa that are larger than, and have a shape distinctly different from, those of the mouse. In four separate experiments with a total of 13 recipient mice, hamster Spermatogenesis was identified in the testes of each mouse. Approximately 6% of the tubules examined demonstrated xenogeneic Spermatogenesis. In addition, cryopreserved hamster testis cells generated Spermatogenesis in recipients. However, abnormalities were noted in hamster spermatids and acrosomes in seminiferous tubules of recipient mice. Hamster spermatozoa were also found in the epididymis of recipient animals, but these spermatozoa generally lacked acrosomes, and heads and tails were separated. Thus, defects in spermiogenesis occur in hamster Spermatogenesis in the mouse, which may reflect a limited ability of endogenous mouse Sertoli cells to support fully the larger and evolutionarily distant hamster germ cell. The generation of Spermatogenesis from frozen hamster cells now adds this species to the mouse and rat, in which spermatogonial stem cells also can be cryopreserved. This finding has immediate application to valuable animals of many species, because the cells could be stored until suitable recipients are identified or culture techniques devised to expand the stem cell population.
Ralph L Brinster - One of the best experts on this subject based on the ideXlab platform.
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xenogeneic Spermatogenesis following transplantation of hamster germ cells to mouse testes
Biology of Reproduction, 1999Co-Authors: Takehiko Ogawa, Ina Dobrinski, Mary R Avarbock, Ralph L BrinsterAbstract:It was recently demonstrated that rat Spermatogenesis can occur in the seminiferous tubules of an immunodeficient recipient mouse after transplantation of testis cells from a donor rat. In the present study, hamster donor testis cells were transplanted to mice to determine whether xenogeneic Spermatogenesis would result. The hamster diverged at least 16 million years ago from the mouse and produces spermatozoa that are larger than, and have a shape distinctly different from, those of the mouse. In four separate experiments with a total of 13 recipient mice, hamster Spermatogenesis was identified in the testes of each mouse. Approximately 6% of the tubules examined demonstrated xenogeneic Spermatogenesis. In addition, cryopreserved hamster testis cells generated Spermatogenesis in recipients. However, abnormalities were noted in hamster spermatids and acrosomes in seminiferous tubules of recipient mice. Hamster spermatozoa were also found in the epididymis of recipient animals, but these spermatozoa generally lacked acrosomes, and heads and tails were separated. Thus, defects in spermiogenesis occur in hamster Spermatogenesis in the mouse, which may reflect a limited ability of endogenous mouse Sertoli cells to support fully the larger and evolutionarily distant hamster germ cell. The generation of Spermatogenesis from frozen hamster cells now adds this species to the mouse and rat, in which spermatogonial stem cells also can be cryopreserved. This finding has immediate application to valuable animals of many species, because the cells could be stored until suitable recipients are identified or culture techniques devised to expand the stem cell population.
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rat Spermatogenesis in mouse testis
Nature, 1996Co-Authors: David E Clouthier, Mary R Avarbock, Shanna D Maika, Robert E Hammer, Ralph L BrinsterAbstract:RECENTLY, transplantation of mouse donor spermatogonial stem cells from a fertile testis to an infertile recipient mouse testis was described1,2. The donor cells established Spermatogenesis in the seminiferous tubules of the host, and normal spermatozoa were produced. In the most successful transplants, the recipient mice were fertile and sired up to 80 per cent of progeny from donor cells2. Here we examine the feasibility of transplanting spermatogonial stem cells from other species to the mouse seminiferous tubule to generate Spermatogenesis. Marked testis cells from transgenic rats were transplanted to the testes of immunodeficient mice, and in all of 10 recipient mice (in 19 of 20 testes), rat Spermatogenesis occurred. Epididymides of eight mice were examined, and the three from mice with the longest transplants (≥ 110 days) contained rat spermatozoa with normal morphology. The generation of rat Spermatogenesis in mouse testes suggests that spermatogonial stem cells of many species could be transplanted, and opens the possibility of xenogeneic Spermatogenesis for other species.
Michael D Griswold - One of the best experts on this subject based on the ideXlab platform.
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the central role of sertoli cells in Spermatogenesis
Seminars in Cell & Developmental Biology, 1998Co-Authors: Michael D GriswoldAbstract:Sertoli cells are the somatic cells of the testis that are essential for testis formation and Spermatogenesis. Sertoli cells facilitate the progression of germ cells to spermatozoa via direct contact and by controlling the environment milieu within the seminiferous tubules. The regulation of Spermatogenesis by FSH and testosterone occurs by the action of these hormones on the Sertoli cells. While the action of testosterone is necessary for Spermatogenesis, the action of FSH minimally serves to promote spermatogenic output by increasing the number of Sertoli cells.
Kazunori Kihara - One of the best experts on this subject based on the ideXlab platform.
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Suppression of Spermatogenesis in ipsilateral and contralateral testicular tissues in patients with seminoma by human chorionic gonadotropin beta subunit
Urology, 2001Co-Authors: Tetsuo Hayashi, Nobuhiko Hyochi, Kazuhiro Ishizaka, Yukio Kageyama, Masahito Suzuki, Gaku Arai, Tetsuo Okuno, Hitoshi Masuda, Satoru Kawakami, Kazunori KiharaAbstract:Objectives. The pathologic complexity of the testicular tumor makes it difficult to demonstrate exactly the relationship between the impaired Spermatogenesis in patients with a testicular tumor and the serum level of the human chorionic gonadotropin beta subunit (beta-hCG). Therefore, we performed quantitative evaluation of Spermatogenesis in ipsilateral and contralateral testicular tissues of seminoma to simplify the relation pathologically and endocrinologically and to demonstrate the exact correlation between Spermatogenesis and serum beta-hCG levels. Methods. Fifty-three biopsy specimens from ipsilateral and contralateral testicular tissues of seminoma were analyzed histologically. The quantitative evaluation of Spermatogenesis was performed by the mean Johnsen’s score count (MJSC). Beta-hCG expression in seminoma was examined immunohistochemically. Serum beta-hCG, testosterone, estradiol, luteinizing hormone, and follicle-stimulating hormone levels were analyzed before orchiectomy. Results. A significant linear relationship (r = −0.82; P
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suppression of Spermatogenesis in ipsilateral and contralateral testicular tissues in patients with seminoma by human chorionic gonadotropin beta subunit
Urology, 2001Co-Authors: Tetsuo Hayashi, Nobuhiko Hyochi, Kazuhiro Ishizaka, Yukio Kageyama, Masahito Suzuki, Gaku Arai, Tetsuo Okuno, Hitoshi Masuda, Satoru Kawakami, Kazunori KiharaAbstract:Objectives. The pathologic complexity of the testicular tumor makes it difficult to demonstrate exactly the relationship between the impaired Spermatogenesis in patients with a testicular tumor and the serum level of the human chorionic gonadotropin beta subunit (beta-hCG). Therefore, we performed quantitative evaluation of Spermatogenesis in ipsilateral and contralateral testicular tissues of seminoma to simplify the relation pathologically and endocrinologically and to demonstrate the exact correlation between Spermatogenesis and serum beta-hCG levels. Methods. Fifty-three biopsy specimens from ipsilateral and contralateral testicular tissues of seminoma were analyzed histologically. The quantitative evaluation of Spermatogenesis was performed by the mean Johnsen’s score count (MJSC). Beta-hCG expression in seminoma was examined immunohistochemically. Serum beta-hCG, testosterone, estradiol, luteinizing hormone, and follicle-stimulating hormone levels were analyzed before orchiectomy. Results. A significant linear relationship (r = −0.82; P <0.005) was found between the serum level of beta-hCG and the MJSC in contralateral testicular tissues but not in ipsilateral ones, although the suppression of Spermatogenesis was observed in both sides without suppression of luteinizing hormone and/or follicle-stimulating hormone production. Conclusions. A clearcut fall in the MJSC with an associated rise in the serum level of beta-hCG was demonstrated in the contralateral testicular tissues but not in the ipsilateral ones of seminoma. It seems most likely that serum beta-hCG suppresses Spermatogenesis in both ipsilateral and contralateral testicular tissues without the suppression occurring through the hypothalamus-pituitary-gonadal system, and also that some less well recognized factors affect Spermatogenesis, making the relation between serum beta-hCG and MJSC obscure in ipsilateral testicular tissues.
Ina Dobrinski - One of the best experts on this subject based on the ideXlab platform.
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Testicular tissue grafting and male germ cell transplantation.
Methods of Molecular Biology, 2012Co-Authors: Jose R. Rodriguez-sosa, Lin Tang, Ina DobrinskiAbstract:Testicular tissue grafting and male germ cell transplantation are techniques that offer unprecedented opportunities to study testicular function and development. While testicular tissue grafting allows recapitulation of testis development and Spermatogenesis from immature males of different mammalian species in recipient mice, germ cell transplantation results in donor-derived Spermatogenesis in recipient testes.Testicular tissue grafting results in Spermatogenesis from a wide variety of large animal donor species and is therefore an attractive way to study testis development and Spermatogenesis and preserve fertility of immature males. Germ cell transplantation represents a functional reconstitution assay for identification of spermatogonial stem cells (SSCs) in a given donor cell population and serves as a valuable tool to study stem cell biology and Spermatogenesis. In this chapter we provide detailed methodology to successfully perform both techniques.
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Suppression of Spermatogenesis before grafting increases survival and supports resurgence of Spermatogenesis in adult mouse testis
Fertility and Sterility, 2012Co-Authors: Lucía Arregui, Rahul Rathi, Mark Modelski, Wenxian Zeng, Eduardo R. S. Roldan, Ina DobrinskiAbstract:Objective To test whether absence of complete Spermatogenesis in mature testicular tissue before grafting will increase graft survival. Design Prospective experimental study. Setting Laboratory. Animal(s) Donor testes were obtained from adult untreated mice, adult mice rendered cryptorchid, and adult mice treated with a GnRH antagonist (acyline). Intervention(s) Donor testes were ectopically grafted to nude mice and recovered at three time points. Main Outcome Measure(s) Most advanced germ cell type and presence of spermatogonia were assessed. Donor testes and grafts were analyzed by histology and by immunocytochemistry for ubiquitin C-terminal hydrolase-L1 to mark germ cells. Result(s) Suppression of Spermatogenesis by inducing cryptorchidism or acyline treatment resulted in improved survival of grafted tissue compared with controls and recovery of complete Spermatogenesis, whereas control testis grafts mostly degenerated and did not restore complete Spermatogenesis. Conclusion(s) These results indicate that complete Spermatogenesis at the time of grafting has a negative effect on graft survival. Grafting of adult testis tissue from donors with suppressed Spermatogenesis leads to spermatogenic recovery and may provide a tool to study and preserve fertility and for conservation of genetic resources in individuals that lack complete germ cell differentiation.
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xenogeneic Spermatogenesis following transplantation of hamster germ cells to mouse testes
Biology of Reproduction, 1999Co-Authors: Takehiko Ogawa, Ina Dobrinski, Mary R Avarbock, Ralph L BrinsterAbstract:It was recently demonstrated that rat Spermatogenesis can occur in the seminiferous tubules of an immunodeficient recipient mouse after transplantation of testis cells from a donor rat. In the present study, hamster donor testis cells were transplanted to mice to determine whether xenogeneic Spermatogenesis would result. The hamster diverged at least 16 million years ago from the mouse and produces spermatozoa that are larger than, and have a shape distinctly different from, those of the mouse. In four separate experiments with a total of 13 recipient mice, hamster Spermatogenesis was identified in the testes of each mouse. Approximately 6% of the tubules examined demonstrated xenogeneic Spermatogenesis. In addition, cryopreserved hamster testis cells generated Spermatogenesis in recipients. However, abnormalities were noted in hamster spermatids and acrosomes in seminiferous tubules of recipient mice. Hamster spermatozoa were also found in the epididymis of recipient animals, but these spermatozoa generally lacked acrosomes, and heads and tails were separated. Thus, defects in spermiogenesis occur in hamster Spermatogenesis in the mouse, which may reflect a limited ability of endogenous mouse Sertoli cells to support fully the larger and evolutionarily distant hamster germ cell. The generation of Spermatogenesis from frozen hamster cells now adds this species to the mouse and rat, in which spermatogonial stem cells also can be cryopreserved. This finding has immediate application to valuable animals of many species, because the cells could be stored until suitable recipients are identified or culture techniques devised to expand the stem cell population.
