[Cell biology and physiology of male reproduction].

Background: An adequate and undisturbed generation of fertile sperm is a prerequisite for fatherhood. Therefore, spermatogenesis is of central importance for male fertility. The testes, however, not only hold the germinal epithelium as the sperm-generating organ but also acts as a gland releasing androgens to control male reproductive function.

Immunocytochemical localization of kisspeptin and kisspeptin receptor in the primate testis.

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.

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

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.

Direct but no transgenerational effects of decitabine and vorinostat on male fertility.

Establishment and maintenance of the correct epigenetic code is essential for a plethora of physiological pathways and disturbed epigenetic patterns can provoke severe consequences, e.g. tumour formation.

Profiling of Cxcl12 receptors, Cxcr4 and Cxcr7 in murine testis development and a spermatogenic depletion model indicates a role for Cxcr7 in controlling Cxcl12 activity.

In mice the chemokine Cxcl12 and its receptor Cxcr4 participate in maintenance of the spermatogonial population during postnatal development. More complexity arises since Cxcl12 also binds to the non-classical/atypical chemokine receptor Cxcr7. We explored the expression pattern of Cxcl12, Cxcr4 and Cxcr7 during postnatal development in mouse testes and investigated the response of Cxcl12, Cxcr4, Cxcr7 and SSC-niche associated factors to busulfan-induced germ cell depletion and subsequent recovery by RNA expression analysis and localization of the proteins.

Sperm competition and the evolution of spermatogenesis.

Spermatogenesis is a long and complex process that, despite the shared overall goal of producing the male gamete, displays striking amounts of interspecific diversity. In this review, we argue that sperm competition has been an important selection pressure acting on multiple aspects of spermatogenesis, causing variation in the number and morphology of sperm produced, and in the molecular and cellular processes by which this happens. We begin by reviewing the basic biology of spermatogenesis in some of the main animal model systems to illustrate this diversity, and then ask to what extent this variation arises from the evolutionary forces acting on spermatogenesis, most notably sperm competition.

Regulation of spermatogenesis: an evolutionary biologist's perspective.

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.

Reassembly of somatic cells and testicular organogenesis in vitro.

Testicular organogenesis in vitro requires an environment allowing a reassembly of testicular cell types. Previous in vitro studies using male murine germ cells cultured in a defined three-dimensional environment demonstrated tubulogenesis and differentiation into spermatozoa. Combining scaffolds as artificial culture substrates with testicular cell culture, we analysed the colonization of collagen sponges by rat testicular cells focusing on cell survival and reassembly of tubule-like-structures in vitro.

Effects of embryo culture media do not persist after implantation: a histological study in mice.

Study Question: Is post-implantation embryonic development after blastocyst transfer affected by exposure to different assisted reproduction technology (ART) culture media?

Summary Answer: Fetal development and placental histology of ART embryos cultured in vitro in different ART media was not impaired compared with embryos grown in vivo.

What Is Known Already: The application of different in vitro culture (IVC) media for human ART has an effect on birthweight of newborns. In the mouse model, differences in blastocyst formation were reported after culture in different ART media.

Germ cell loss is associated with fading Lin28a expression in a mouse model for Klinefelter's syndrome.

Klinefelter's syndrome is a male sex-chromosomal disorder (47,XXY), causing hypogonadism, cognitive and metabolic deficits. The majority of patients are infertile due to complete germ cell loss after puberty. As the depletion occurs during development, the possibilities to study the underlying causes in humans are limited.

A combined approach facilitates the reliable detection of human spermatogonia in vitro.

Study Question: Does a combined approach allow for the unequivocal detection of human germ cells and particularly of spermatogonia in vitro?

Summary Answer: Based on our findings, we conclude that an approach comprising: (i) the detailed characterization of patients and tissue samples prior to the selection of biopsies, (ii) the use of unambiguous markers for the characterization of cultures and (iii) the use of biopsies lacking the germ cell population as a negative control is the prerequisite for the establishment of human germ cell cultures.

What Is Known Already: The use of non-specific marker genes and the failure to assess the presence of testicular somatic cell types in germ cell cultures may have led to a misinterpretation of results and the erroneous description of germ cells in previous studies.

Study Design, Size, Duration: Testicular biopsies were selected from a pool of 264 consecutively obtained biopsies.

Quantitative bioimaging of platinum in polymer embedded mouse organs using laser ablation ICP-MS.

A novel quantification approach for tissue imaging using laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) based on tissue embedding in cold-curing resins (Technovit 7100) is presented. With respect to massive side effects on cisplatin, the platinum distribution at different time intervals after cisplatin treatment of mice was determined quantitatively in different tissues including cochlea, testis and kidney. For this purpose, cold-curing resin blocks spiked with different amounts of platinum acetyl acetonate prior to curing were ablated after sectioning at 5 μm thickness and were analysed using ICP-MS after microwave digestion.

Raman microspectroscopic discrimination of TCam-2 cultures reveals the presence of two sub-populations of cells.

TCam-2 cells are the main in vitro model for investigations into seminomatous tumors. However, despite their widespread use, questions remain regarding the cells' homogeneity and consequently how representative they are of seminomas. We assess the TCam-2 cell line using routine and novel authentication methods to determine its homogeneity, identify any cellular sub-populations and resolve whether any changes could be due to generational differentiation.

Intratesticular action of kisspeptin in rhesus monkey (Macaca mulatta).

Kisspeptin-Kiss1R signalling in mammals has been implicated as an integral part of the reproductive cascade. Kisspeptinergic neurons upstream of GnRH neurons are involved in the activation of the hypothalamic GnRH pulse generator during pubertal onset. Thus, the major research focus has been on the central effects of kisspeptin.

Experimental endocrine manipulation by contraceptive regimen in the male marmoset (Callithrix jacchus).

Marmosets are used as preclinical model in reproductive research. In contrast to other primates, they display short gestation times rendering this species valid for exploration of effects on fertility. However, their peculiar endocrine regulation differs from a those of macaques and humans.

Fact or fiction: In vitro spermatogenesis.

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.

Autologous ectopic grafting of cryopreserved testicular tissue preserves the fertility of prepubescent monkeys that receive sterilizing cytotoxic therapy.

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.

Comparative marker analysis after isolation and culture of testicular cells from the immature marmoset.

The marmoset monkey is a valuable model in reproductive medicine. While previous studies have evaluated germ cell dynamics in the postnatal marmoset, the features of testicular somatic cells remain largely unknown. Therefore, the aim of this study was to establish marmoset-specific markers for Sertoli and peritubular cells (PTCs) and to compare protocols for the enrichment and culture of testicular cell types.

The pluripotency factor LIN28 in monkey and human testes: a marker for spermatogonial stem cells?

Mammalian spermatogenesis is maintained by spermatogonial stem cells (SSCs). However, since evidentiary assays and unequivocal markers are still missing in non-human primates (NHPs) and man, the identity of primate SSCs is unknown. In contrast, in mice, germ cell transplantation studies have functionally demonstrated the presence of SSCs.

Developmental expression of the pluripotency factor sal-like protein 4 in the monkey, human and mouse testis: restriction to premeiotic germ cells.

SALL4 (sal-like protein 4) is a pluripotency transcription factor, which is highly expressed in embryonic stem (ES) cells and which is essential for mouse preimplantation development. In adult mouse organs, Sall4 mRNA is highly expressed in the testis and ovary, while there is only little or no expression in other organs. There is also a high expression of SALL4 in human testicular germ cell tumors.

Effects of different storage protocols on cat testis tissue potential for xenografting and recovery of spermatogenesis.

The loss of genetic diversity due to premature death of valuable individuals is a significant problem in animal conservation programs, including endangered felids. Testis tissue xenografting has emerged as a system to obtain spermatozoa from dead immature animals, however protocols to store this tissue before xenografting are still lacking. This study focused on testis tissue cryopreservation and storage from the domestic cat (Felis catus) classified as "pre-pubertal" and "pubertal" according to spermatogenesis development.

Immature rhesus monkey (Macaca mulatta) testis xenografts show increased growth, but not enhanced seminiferous differentiation, under human chorionic gonadotropin treatment of nude mouse recipients.

Prepubertal male cancer patients facing gonadotoxic therapy cannot be offered a procedure to create a fertility reserve, in contrast to the options available for men. Sperm production by testis xenografting has been proposed for boys, but as the efficacy of sperm production in animal trials is low, hormonal stimulation of recipients carrying xenografts has been proposed to enhance graft development. We confirm that spermatogonia are the only germ cells present in immature rhesus testis.

Testicular recovery after irradiation differs in prepubertal and pubertal non-human primates, and can be enhanced by autologous germ cell transplantation.

Background: Although infertility is a serious concern in survivors of pediatric cancers, little is known about the influence of the degree of sexual maturation at the time of irradiation on spermatogenic recovery after treatment. Thus, we address this question in a non-human primate model, the rhesus monkey (Macaca mulatta).

Methods: Two pubertal (testis size 3 and 6.

Reduced expression of DNMT3B in the germ cells of patients with bilateral spermatogenic arrest does not lead to changes in the global methylation status.

DNA methylation events during spermatogenesis have important implications for gamete integrity and transmission of epigenetic information to the next generation. However, the role of DNA methyltransferases in the disorders of human spermatogenesis has not been elucidated. The aim of the present study was to evaluate the expression of DNMT3B, crucial for full germ cell methylation, in testicular germ cells of patients with spermatogenic arrest and to determine whether or not there is an association with the global methylation status.

Testicular function and fertility preservation in male cancer patients.

The testis has been shown to be highly susceptible to the toxic effects of cancer therapy at all stages of life. Young cancer survivors are approximately half as likely as their siblings to sire a pregnancy. Radiation therapy to the testes and high cumulative dose of alkylating agents are the major factors decreasing the probability of fertility.