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  1. Article ; Online: Regulation of spermatogenesis: an evolutionary biologist's perspective.

    Schlatt, Stefan / Ehmcke, Jens

    Seminars in cell & developmental biology

    2014  Volume 29, Page(s) 2–16

    Abstract: This review describes the regulation of spermatogenesis taking into consideration the hypothalamic-pituitary gonadal axis, the male reproductive organs and the endocrine and paracrine factors involved in the control of sperm production and the release of ...

    Abstract This review describes the regulation of spermatogenesis taking into consideration the hypothalamic-pituitary gonadal axis, the male reproductive organs and the endocrine and paracrine factors involved in the control of sperm production and the release of androgens. Instead of detailed descriptions of many hormones and growth factors, we attempt to provide an integrative and evolutionary view by comparing different species and considering their specific needs for successful male reproduction. The review focuses on species specific differences in the structural organization of spermatogenesis and indicates that the crucial regulatory mechanisms controlling sperm output are targeted toward differentiating spermatogonia when they initiate clonal expansion. We argue that the further differentiation of germ cells is following a highly coordinated and strictly predetermined morphogenetic cascade widely independent of hormonal control. We propose a hypothetical "ancient" model. Spermatogenesis and steroidogenesis are controlled by a master switch (GnRH pulse generator) under whose control two separate feedback systems provide independent control of androgen (LH-testosterone) and sperm production (FSH-inhibin). This scenario offers high flexibility and has seen uncountable adaptions to optimize the specific needs of different species. Models for the hormonal regulation in hamsters, laboratory rodents and primates are presented to illustrate the species specific diversity.
    MeSH term(s) Animals ; Cell Differentiation ; Cell Proliferation ; Cricetinae ; Follicle Stimulating Hormone/metabolism ; Gonadotropin-Releasing Hormone/metabolism ; Humans ; Inhibins/biosynthesis ; Luteinizing Hormone/metabolism ; Macaca ; Male ; Mice ; Rats ; Spermatogenesis/physiology ; Spermatogonia/cytology ; Spermatozoa/cytology ; Testis/physiology ; Testosterone/biosynthesis
    Chemical Substances Gonadotropin-Releasing Hormone (33515-09-2) ; Testosterone (3XMK78S47O) ; Inhibins (57285-09-3) ; Luteinizing Hormone (9002-67-9) ; Follicle Stimulating Hormone (9002-68-0)
    Language English
    Publishing date 2014-05
    Publishing country England
    Document type Journal Article ; Review
    ZDB-ID 1312473-0
    ISSN 1096-3634 ; 1084-9521
    ISSN (online) 1096-3634
    ISSN 1084-9521
    DOI 10.1016/j.semcdb.2014.03.007
    Database MEDical Literature Analysis and Retrieval System OnLINE

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    In stock of ZB MED Cologne/Königswinter

    Zs.A 2918: Show issues Location:
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  2. Article ; Online: Immunocytochemical localization of kisspeptin and kisspeptin receptor in the primate testis.

    Irfan, Shahzad / Ehmcke, Jens / Shahab, Muhammad / Wistuba, Joachim / Schlatt, Stefan

    Journal of medical primatology

    2016  Volume 45, Issue 3, Page(s) 105–111

    Abstract: Background: Hypothalamic kisspeptin-kisspeptin receptor signalling in primates ensures the successful progression into puberty during development and maintenance of reproductive capacity during adulthood. Human testis has been shown to express high-to- ... ...

    Abstract Background: Hypothalamic kisspeptin-kisspeptin receptor signalling in primates ensures the successful progression into puberty during development and maintenance of reproductive capacity during adulthood. Human testis has been shown to express high-to-moderate levels of kisspeptin and kisspeptin receptor gene expression. In this study, we aimed at characterizing the localization of kisspeptin and kisspeptin receptor in adult primate testis tissue.
    Methods: Immunocytochemistry was performed on paraffin-embedded testicular sections from adult rhesus monkeys and from common marmoset monkeys.
    Results: Kisspeptin receptor was detected in Sertoli cells in the periphery of the seminiferous tubules in adult testes of both species. In contrast, kisspeptin was not localized in the seminiferous epithelium and was detected only in the interstitial compartment of the adult rhesus monkey testis.
    Conclusion: Kisspeptin receptor and kisspeptin are localized in the testis of Old World and New World primates.
    MeSH term(s) Animals ; Callithrix/metabolism ; Immunohistochemistry ; Kisspeptins/metabolism ; Macaca mulatta/metabolism ; Male ; Receptors, G-Protein-Coupled/metabolism ; Seminiferous Tubules/chemistry ; Sertoli Cells/chemistry ; Species Specificity ; Testis/chemistry
    Chemical Substances Kisspeptins ; Receptors, G-Protein-Coupled
    Language English
    Publishing date 2016-06
    Publishing country Denmark
    Document type Journal Article
    ZDB-ID 121206-0
    ISSN 1600-0684 ; 0047-2565
    ISSN (online) 1600-0684
    ISSN 0047-2565
    DOI 10.1111/jmp.12212
    Database MEDical Literature Analysis and Retrieval System OnLINE

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    Zs.A 819: Show issues Location:
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  3. Book ; Online ; Thesis: Technology, firm performance and market structure

    Schmidt-Ehmcke, Jens [Verfasser]

    2009  

    Author's details von Jens Schmidt-Ehmcke
    Keywords Wirtschaft ; Economics
    Subject code sg330
    Language English
    Document type Book ; Online ; Thesis
    Database Digital theses on the web

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  4. Article ; Online: Lower total cell numbers in mouse preimplantation embryos cultured in human assisted reproductive technique (ART) media are not induced by apoptosis.

    Schulte, Katharina / Ehmcke, Jens / Schlatt, Stefan / Boiani, Michele / Nordhoff, Verena

    Theriogenology

    2015  Volume 84, Issue 9, Page(s) 1620–1630

    Abstract: A common feature of assisted reproductive techniques such as IVF or intracytoplasmic sperm injection is the IVC of oocytes or preimplantation embryos in artificial culture media. The IVC conditions are selected to mimic the environment of the female ... ...

    Abstract A common feature of assisted reproductive techniques such as IVF or intracytoplasmic sperm injection is the IVC of oocytes or preimplantation embryos in artificial culture media. The IVC conditions are selected to mimic the environment of the female genital tract. We have shown that murine preimplantation embryos respond to different culture media with changes in developmental rates, cellular lineage composition, and gene expression patterns. In this study, we explored whether apoptosis is responsible for cell loss in mouse preimplantation embryos after exposure to different human culture media. We examined total embryonic cell count as well as the pattern of protein expression for caspase-9 (intrinsic pathway), caspase-8 (extrinsic pathway), and the executioner caspase-3 via immunohistochemical staining. Total cell counts decline in embryos cultured either in innovative sequential medium 1 and Blast Assist (Origio) or human tubal fluid and MultiBlast (Irvine Scientific) when compared to KSOM(aa). Few cells were caspase-9 and -3 positive in all experimental groups. Staining for caspase-8 was almost undetectable. We conclude that embryonic cell loss is not associated with higher rates of intrinsic apoptotic cell loss. Our results suggest that the culture medium-dependent decline in total cell count and the developmental restriction in embryos cultured in innovative sequential medium 1/Blast Assist and human tubal fluid/MultiBlast are related to processes affecting cell proliferation.
    MeSH term(s) Animals ; Apoptosis/drug effects ; Blastocyst/physiology ; Culture Media ; Embryo Culture Techniques/methods ; Embryo Transfer ; Female ; Male ; Mice
    Chemical Substances Culture Media
    Language English
    Publishing date 2015-12
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 189232-0
    ISSN 1879-3231 ; 0093-691X
    ISSN (online) 1879-3231
    ISSN 0093-691X
    DOI 10.1016/j.theriogenology.2015.08.009
    Database MEDical Literature Analysis and Retrieval System OnLINE

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    In stock of ZB MED Cologne/Königswinter

    Zs.A 3929: Show issues Location:
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  5. Article: Fact or fiction: In vitro spermatogenesis.

    Reuter, Karin / Schlatt, Stefan / Ehmcke, Jens / Wistuba, Joachim

    Spermatogenesis

    2012  Volume 2, Issue 4, Page(s) 245–252

    Abstract: Many previous studies have aimed at spermatogenesis of male murine germ cells in vitro, but no efficient system has been established yet that covers the entire process of mammalian spermatogenesis in a culture dish permanently. In this review, we report ... ...

    Abstract Many previous studies have aimed at spermatogenesis of male murine germ cells in vitro, but no efficient system has been established yet that covers the entire process of mammalian spermatogenesis in a culture dish permanently. In this review, we report on the requirements of spermatogenesis and the current state of different culture methods using testicular tissue fragments, single cell suspensions or three-dimensional culture environments.
    Language English
    Publishing date 2012-11-28
    Publishing country United States
    Document type Journal Article
    ZDB-ID 2629571-4
    ISSN 2156-5562 ; 2156-5554
    ISSN (online) 2156-5562
    ISSN 2156-5554
    DOI 10.4161/spmg.21983
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  6. Book ; Thesis: Schädel, Bezahnung und Oviduct - fortpflanzungsbiologische Aspekte bei Salamandern des südlichen Mittelamerika

    Ehmcke, Jens

    2002  

    Author's details Jens Ehmcke
    Keywords Geschlechtsunterschied ; Histologie ; Zahn ; Eileiter ; Schädel ; Lungenlose Salamander ; Mittelamerika
    Language German
    Size 236 S, Ill, 24 cm
    Publisher Schüling
    Publishing place Münster
    Document type Book ; Thesis
    Thesis / German Habilitation thesis Univ., Diss--Münster (Westfalen), 2002
    ISBN 3934849881 ; 9783934849884
    Database Former special subject collection: coastal and deep sea fishing

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  7. Book ; Thesis: Schädel, Bezahnung und Oviduct - fortpflanzungsbiologische Aspekte bei Salamandern des südlichen Mittelamerika

    Ehmcke, Jens

    2002  

    Author's details Jens Ehmcke
    Keywords Geschlechtsunterschied ; Histologie ; Zahn ; Eileiter ; Schädel ; Lungenlose Salamander ; Mittelamerika
    Language German
    Size 236 S, Ill, 24 cm
    Publisher Schüling
    Publishing place Münster
    Document type Book ; Thesis
    Thesis / German Habilitation thesis Univ., Diss--Münster (Westfalen), 2002
    ISBN 3934849881 ; 9783934849884
    Database Special collection on veterinary medicine and general parasitology

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  8. Article ; Online: Animal models for fertility preservation in the male.

    Ehmcke, Jens / Schlatt, Stefan

    Reproduction (Cambridge, England)

    2008  Volume 136, Issue 6, Page(s) 717–723

    Abstract: Fertility preservation in the male is routinely focused on sperm. In clinical and veterinary settings, cryopreservation of sperm is a widely used tool. However, the goals for male fertility preservation differ between experimental models, maintenance of ... ...

    Abstract Fertility preservation in the male is routinely focused on sperm. In clinical and veterinary settings, cryopreservation of sperm is a widely used tool. However, the goals for male fertility preservation differ between experimental models, maintenance of livestock, conservation of rare species, and fertility protection in men. Therefore very different approaches exist, which are adapted to the specialized needs for each discipline. Novel tools for male fertility preservation are explored targeting immature germ cells in embryonic or immature testes. Many options might be developed to combine germline preservation and generation of sperm ex vivo leading to interesting new perspectives. This review highlights current and future options for male fertility preservation with a special focus on animal models and a consideration of the various disciplines in need of novel tools.
    MeSH term(s) Animals ; Cryopreservation/methods ; Humans ; Infertility, Male/prevention & control ; Male ; Models, Animal ; Organ Preservation/methods ; Organ Preservation/veterinary ; Semen Preservation/methods ; Semen Preservation/veterinary ; Spermatozoa ; Testis
    Language English
    Publishing date 2008-12
    Publishing country England
    Document type Journal Article ; Research Support, N.I.H., Extramural ; Review
    ZDB-ID 2034501-X
    ISSN 1741-7899 ; 1470-1626 ; 1476-3990
    ISSN (online) 1741-7899
    ISSN 1470-1626 ; 1476-3990
    DOI 10.1530/REP-08-0093
    Database MEDical Literature Analysis and Retrieval System OnLINE

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    Uc I Zs.362: Show issues Location:
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  9. Article: Identification and characterization of spermatogonial subtypes and their expansion in whole mounts and tissue sections from primate testes.

    Ehmcke, Jens / Schlatt, Stefan

    Methods in molecular biology (Clifton, N.J.)

    2008  Volume 450, Page(s) 109–118

    Abstract: The different types of spermatogonia present in the testes of all mammalian species have a series of functions in the adult testis. Some cycle regularly to (1) maintain the spermatogonial population and (2) derive differentiating germ cells to maintain ... ...

    Abstract The different types of spermatogonia present in the testes of all mammalian species have a series of functions in the adult testis. Some cycle regularly to (1) maintain the spermatogonial population and (2) derive differentiating germ cells to maintain continuous spermatogenesis; other spermatogonia act as a functional reserve, proliferating only very rarely under healthy conditions but repopulating the depleted seminiferous tubules after gonadotoxic insult. The number, appearance, and function of different types of spermatogonia differ greatly between mammalian species, and therefore the precise number of mitotic steps and the number of identifiable stages in spermatogenesis, the sperma-togenic efficiency, and the histological appearance of the seminiferous epithelium show remarkable variation. To characterize spermatogonial phenotypes and their respective functions and to understand the kinetics of spermatogenesis in any given species, a series of methods can be combined for best results. Conventional (hema-toxylin or Periodic acid Schiff's reagent PAS/hematoxylin) staining on sections allows histological identification of the different types of spermatogonia and stages of spermatogenesis in the tissue. Immunohistochemical detection of the proliferation marker bromodeoxyuridine (BrdU) in sections and whole mounts of seminiferous tubules allows determination of which types of spermatogonia proliferate in which stage of spermatogenesis and determine the sizes of clones of proliferation spermatogonia in each stage. Combined, these methods allow the best possible characterization of spermatogenesis in any given mammalian species.
    MeSH term(s) Animals ; Bromodeoxyuridine/metabolism ; Histocytological Preparation Techniques/methods ; Immunohistochemistry ; Macaca mulatta/anatomy & histology ; Macaca mulatta/metabolism ; Male ; Primates/anatomy & histology ; Primates/metabolism ; Spermatogenesis ; Spermatogonia/classification ; Spermatogonia/cytology ; Spermatogonia/metabolism ; Staining and Labeling ; Testis/cytology ; Testis/metabolism ; Tissue Embedding ; Tissue Fixation
    Chemical Substances Bromodeoxyuridine (G34N38R2N1)
    Language English
    Publishing date 2008
    Publishing country United States
    Document type Journal Article
    ISSN 1064-3745
    ISSN 1064-3745
    DOI 10.1007/978-1-60327-214-8_7
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  10. Article ; Online: Autologous ectopic grafting of cryopreserved testicular tissue preserves the fertility of prepubescent monkeys that receive sterilizing cytotoxic therapy.

    Jahnukainen, Kirsi / Ehmcke, Jens / Nurmio, Mirja / Schlatt, Stefan

    Cancer research

    2012  Volume 72, Issue 20, Page(s) 5174–5178

    Abstract: Boys faced with future sterility as a result of the need of a sterilizing cancer therapy might avoid this fate by engraftment of cryopreserved immature testicular tissue after therapy is completed. Efforts to address this important survivorship issue ... ...

    Abstract Boys faced with future sterility as a result of the need of a sterilizing cancer therapy might avoid this fate by engraftment of cryopreserved immature testicular tissue after therapy is completed. Efforts to address this important survivorship issue have been encouraged by reports of the long-term survival and proliferation of human spermatogonia after xenotransplant of cryopreserved immature testicular tissue into immunocompromised murine hosts. However, spermatogenic arrest at the pachytene spermatocyte stage that occurs in this situation has been associated with a failure in sperm production. In this study, we used a prepubescent simian model to address the possibility that testicular tissue engraftment is insufficiently supported in the model to allow suitable maturation of germ cells. Briefly, we carried out autologous orthotopic grafting of cryopreserved testicular tissue from four prepubescent monkeys and one pubescent rhesus monkey after testicular irradiation and castration of the host animal. Five months after implantation of scrotal grafts, we determined that 3% to 7% of the autografts could be recovered with spermatogenesis proceeding through spermatozoa formation in 13% to 17% of the seminiferous tubules formed in the grafts. In contrast, Sertoli cell-only tubules were detected in parallel xenografts transplanted into immunocompromised mice. Our results show that cryopreservation of testicular tissue from prepubescent primates can maintain the fully functional capacity of spermatogonia to produce sperm, but that host conditions are critical for spermatogenic maturation. Furthermore, our results establish an initial perspective on the quantity of cryopreserved material needed to ensure success in preserving fertility through testicular tissue grafts.
    MeSH term(s) Animals ; Antineoplastic Agents/toxicity ; Cryopreservation ; Fertility/drug effects ; Macaca mulatta ; Male ; Sexual Maturation ; Testis/transplantation
    Chemical Substances Antineoplastic Agents
    Language English
    Publishing date 2012-08-17
    Publishing country United States
    Document type Journal Article ; Research Support, N.I.H., Extramural ; Research Support, Non-U.S. Gov't
    ZDB-ID 1432-1
    ISSN 1538-7445 ; 0008-5472
    ISSN (online) 1538-7445
    ISSN 0008-5472
    DOI 10.1158/0008-5472.CAN-12-1317
    Database MEDical Literature Analysis and Retrieval System OnLINE

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