DigitalUM :: Browsing by Subject "Spermatogenesis"

Browsing by Subject "Spermatogenesis"

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Open Access
Connexin 43: its regulatory role in testicular junction dynamics and spermatogenesis
(F. Hernández y J.F. Madrid. Murcia: Universidad de Murcia, Departamento de Biología Celular e Histología., 2011) Weider, Karola; Bergmann, Martin; Brehm, Ralph
Spermatogenesis is an intensely regulated process of germ cell development which takes place in the seminiferous tubules of the testis. In addition to known endocrine and autocrine/paracrine signaling pathways, there is now strong evidence that direct intercellular communication via gap junction channels and their specific connexins represents an important mechanism in the regulation of spermatogenesis. Another possibility is that connexins may indirectly regulate the spermatogenic process through modulation of tight and adherens junction proteins, further main structural components of the Sertoli-Sertoli junctional complexes at the blood-testis barrier site. The present review is focused on connexin 43 and updates its possible roles and functions in testicular junction dynamics and in the initiation and maintenance of spermatogenesis. In addition, testicular phenotypes of recently generated (1) conventional connexin 43 knockout mice, (2) connexin 43 knockin mice and (3) transgenic mice exhibiting a cell-specific (conditional) connexin 43 knockout will be discussed.
Open Access
Emergent roles for intercellular adhesion molecule-1 in the restructuring of the blood-testis barrier during spermatogenesis in the mammal
(Universidad de Murcia. Departamento de Biología Celular e Histología, 2016) Mruk, Dolores D.
Mammalian spermatogenesis is comprised of a series of molecular, cellular, and morphological events that underscore the movement of developing germ cells across the blood-testis barrier. These events involve the restructuring of tight junctions, basal ectoplasmic specializations, gap junctions, and desmosomes, which constitute blood-testis barrier function. Previous studies show that preleptotene/leptotene spermatocytes traverse the blood-testis barrier while transiently trapped within an intermediate compartment, which sequesters primary spermatocytes away from basal and adluminal compartments of the seminiferous epithelium. Preleptotene/leptotene spermatocytes enter the adluminal compartment when stable junctions ahead of spermatocytes disassemble, while new junctions assemble behind them. While there is enormous restructuring of the seminiferous epithelium, the mechanism of germ cell movement is incompletely understood. In this perspective, the significance of intercellular adhesion molecule-1 in the restructuring of the blood-testis barrier during spermatogenesis in the mammal is discussed.
Open Access
Expression of the GABAA receptor/Chloride Channel in murine spermatogenic cells
(Murcia: F. Hernández, 2011) Kanbara, Kiyoto; Mori, Yoshiaki; Kubota, Takahiro; Watanabe, Masahito; Yanagawa, Yuchio; Otsuki, Yoshinori
Previous studies from our laboratory have demonstrated that γ-aminobutyric acid (GABA) and GABAB receptor subunits are expressed within the acrosome of spermatids during spermiogenesis. Furthermore, our previous study with the glutamate decarboxylase (GAD) 67-GFP knock-in mouse demonstrated that GFP–positive cells were localized to the epithelium of the caput of epididymis. In the present study, we detected GABAA subunits, including α1, α5, ß1-3 and γ3, and both isoforms of GAD, GAD65 and GAD67, in mouse spermatogenic cells using RT-PCR. The expression of these proteins was subsequently confirmed by western blot analysis. Immunohistochemistry also revealed that GABA, GAD65, and α5, ß1 and γ3 subunits of the GABAA receptor were localized in the membrane of spermatogenic cells, including spermatocytes and spermatids. The whole-cell patchclamp analysis demonstrated that GABA application induced an inward chloride current in some of the large and round spermatogenic cells. Our findings show that spermatogenic cells have a GABA producing system by themselves, and that GABA may function via the ionotropic GABAA receptor. This data suggests that the GABAergic system may play important roles in the male reproductive system.
Open Access
How does retinoic acid (RA) signaling pathway regulate spermatogenesis?
(Universidad de Murcia, Departamento de Biologia Celular e Histiologia, 2022) Zhang, Hua Zhe; Hao, Shuang Li; Yang, Wan Xi
Male sterility is a worldwide health problem which has troubled many unfortunate families and attracted widespread attention in the field of reproduction. Retinoic acid (RA) is a metabolite of vitamin A. Previous studies have shown that insufficient intake of vitamin A can lead to male infertility. Similarly, RA-deficiency can lead to abnormal spermatogenesis in men. RA signaling is inseparable from hormone stimulation, such as FSH, testosterone and others. It can regulate spermatogenesis as well, including the proliferation and differentiation of spermatogonia, meiosis, spermiogenesis and spermiation. To promote or inhibit spermatogenesis, RA regulates Stra8, Kit, GDNF, BMP4 and other factors in various pathways. At the self-renewal stage, RA inhibits spermatogonia renewal by directly or indirectly inhibiting DMRT, GDNF and Cyclin. At the stage of differentiation and meiosis, RA controls SSC differentiation through Kit induction and Nanos2 inhibition, and controls spermatogonia meiotic entry through up- regulation of Stra8. At the stage of spermiogenesis, RARα, as a key regulator, regulates spermatogenesis by up regulating Stra8 while binding with RA. Although RA plays an important role in all stages of spermatogenesis, RA signaling is more important in the early stage of spermatogonia (spg) differentiation and spermatocyte (spc) meiosis. According to the principle of RA signaling that regulates spermatogenesis, we also speculate on the future clinical application of RA, such as potential induction of SSC in vitro, contraception and restoring spermatogenesis. This paper reviews the regulatory pathways of RA, and prospects the clinical applications of RA signaling in the future.
Open Access
IGSF4: a new intercellular adhesion molecule that is called by three names, TSLC1, SgIGSF and SynCAM, by virtue of its diverse function
(Murcia : F. Hernández, 2003) Watanabe, K.; Ito, A.; Koma, Y.; Kitamura, Y.
Members of the immunoglobulin superfamily often play key roles in intercellular adhesion. IGSF4 is a novel immunoglobulin (Ig)-like intercellular adhesion molecule. Three Ig-like domains are included in the extracellular domain of IGSF4 and mediate homophilic or heterophilic interactions independently of Ca2+. The cytoplasmic domain of IGSF4 contains the binding motifs that connect to actin fibers. Since IGSF4 has been characterized by several independent research groups, this molecule is called by three names, TSLC1, SgIGSF and SynCAM. IGSF4 was first characterized as a tumor suppressor of non-small cell lung cancer and termed TSLC1, although how IGSF4 suppresses tumor growth remains unknown. Silencing of the IGSF4 gene was primarily achieved by allelic loss and promoter methylation in this type of cancers. Soon after this discovery, IGSF4 was found to have roles in adhesion of spermatogenic cells to Sertoli cells and mast cells to fibroblasts and termed SgIGSF. Other researchers revealed that IGSF4 drives synaptic formation of neural cells and termed it SynCAM.
Open Access
Lectin-binding pattern of Senegalese sole Solea senegalensis (Kaup) testis
(Murcia : F. Hernández, 2010) Desantis, S.; Zizza, S.; García-López, A.; Sciscioli, V.; Mañanos, E.; De Metrio, V.G.; Sarasquete, C.
The localization and characterization of oligosaccharide sequences in the testis of Senegalese sole Solea senegalensis was investigated using 12 lectins in combination with KOH saponification and sialidase digestion (K-s). The interstitial compartment contained all the sugar residues investigated, those bearing oligosaccharides terminating with sialic acid (Neu5Ac) α2,3Galß1,4GlcNAc, Neu5AcGalNAcα1,3(LFucß1,2)Galß1,3/4GlcNAcß1 and GalNAcα1,3(LFuc1,2)Galß1,3/4GlcNAcß1 being more abundant in the medullar region than in the cortex. The melano-macrophage centres found in the interstitial compartment displayed glycans terminating with Galß1,3GalNAc. The basal lamina separating the germinal and interstitial compartments exhibited glycans with terminal/internal mannose, internal ßGlcNAc, and terminal Neu5Acα2,6Gal/GalNAc, and Neu5AcGalß1,3GalNAc, Galß1,3GalNAc (PNA), Galß1,4GlcNAc, GalNAc, αGal, and αL-Fuc. In the germinal compartment, the Sertoli cells expressed only glycans terminating with Neu5Acα2,3Galß1,4GlcNAc in the apical and supra-nuclear lateral surface of the spermatonial cysts located in the distal part of the seminiferous lobules. Primary spermatocytes exhibited oligosaccharides terminating with Galß1,3GalNAc and αGalNAc in the cytoplasm and nucleus, respectively. The spermatids contained highly mannosylated glycans terminating with GalNac, αGal, and αL-Fuc. The head of spermatozoa expressed a more complex glycosylation pattern characterized by the additional presence of oligosaccharides terminating with Neu5Acα2,3Galß1,4GlcNAc, Neu5AcGalß1,3GalNAc, Neu5AcGalNAcα1,3(LFucα1,2)Galß1,3/4GlcNAcß1, GalNAcα1,3(LFucα1,2)Galß1,3/4GlcNAcß1. The comparison with previous lectin histochemical studies carried out in other fish species reveals a specific glycosylation pattern of Senegalese sole testicular structures and spermatozoa head
Open Access
Loss of connexin43 (Cx43) in Sertoli cells leads to spatio-temporal alterations in occludin expression
(F. Hernández y Juan F. Madrid. Universidad de Murcia. Departamento de Biología Celular e Histología, 2014) Gerber, Jonathan; Weider, Karola; Hambruch, Nina; Brehm, Ralph
Within the testis, Sertoli cell (SC) junctional complexes between somatic SC create a basal and apical polarity within the seminiferous epithelium, restrict movement of molecules between cells, and separate the seminiferous epithelium into a basal and adluminal compartment. This barrier consists of membrane integrated proteins known as tight, adherens, and gap junctions, which promote cell-cell contact along the blood-testis-barrier (BTB). Nevertheless, these junctions, which form the basis of the BTB are structures whose function and dynamic regulation is still poorly understood. Thus, in this study, through the use of immunohistochemistry (IHC), semi quantitative western blot (WB) analysis, and real-time-quantitative-PCR (qRT-PCR) we focused on the expression pattern of the main testicular tight junction protein, occludin, in SC. For this, the established transgenic SC specific connexin 43 (Cx43) knockout (SCCx43KO) mouse line was used; both knockout (KO) and wildtype (WT) males of different ages from juvenile to adult were compared. The object was to elucidate a possible role of Cx43 on the expression pattern and regulation of occludin. This conditional KO mouse line lacks the gap junction gene Gja1 (coding for Cx43) only in SC and reveals impaired spermatogenesis. The qRT-PCR indicates an increase in occludin mRNA in adult KO mice. These results correspond to the occludin protein synthesis of adult mice. Additionally, during puberty, occludin localization at the BTB barrier in KO mice is delayed. Our study demonstrates spatiotemporal alterations in occludin mRNA- and protein-expression, indicating that Cx43 might act as a regulator for BTB formation (and function).
Open Access
Mammalian spermatogenesis investigated by genetic engineering
(Murcia : F. Hernández, 1999) Escalier, D.
Genes involved in mammal spermatogenesis can now be identified through mutants created by genetic engineering. Information has been obtained on male meiosis, but also on the factors regulating the proliferation, maintenance and differentiation of male germ cells. Its has also increased our knowledge of the germ cell phenotype emerging from an altered germ cell genotype. This review is focused on data from genes expressed in male germ cells and on the question of how germ cells and Sertoli cells cope with the molecular lesions induced. The conservation of a wild-type phenotype of male germ cells in mutant mice is discussed, and how the mouse genetic background can lead to different germ cell phenotypes for a given gene mutation.
Open Access
Mammalian target of rapamycin complex (mTOR) pathway modulates blood-testis barrier (BTB) function through F-actin organization and gap junction
(2016) Li, Nan; Yan Cheng, C.
mTOR (mammalian target of rapamycin) is one of the most important signaling molecules in mammalian cells which regulates an array of cellular events, ranging from cell metabolism to cell proliferation. Based on the association of mTOR with the core component proteins, such as Raptor (regulatoryassociated protein of mTOR) or Rictor (rapamycinintensive companion of mTOR), mTOR can become the mTORC1 (mammalian target of rapamycin complex 1) or mTORC2, respectively. Studies have shown that during the epithelial cycle of spermatogenesis, mTORC1 promotes remodeling and restructuring of the bloodtestis barrier (BTB) in vitro and in vivo, making the Sertoli cell tight junction (TJ)-permeability barrier “leaky”; whereas mTORC2 promotes BTB integrity, making the Sertoli cell TJ-barrier “tighter”. These contrasting effects, coupled with the spatiotemporal expression of the core signaling proteins at the BTB that confer the respective functions of mTORC1 vs. mTORC2 thus provide a unique mechanism to modulate BTB dynamics, allowing or disallowing the transport of biomolecules and also preleptotene spermatocytes across the immunological barrier. More importantly, studies have shown that these changes to BTB dynamics conferred by mTORC1 and mTORC2 are mediated by changes in the organization of the actin microfilament networks at the BTB, and involve gap junction (GJ) intercellular communication. Since GJ has recently been shown to be crucial to reboot spermatogenesis and meiosis following toxicant-induced aspermatogenesis, these findings thus provide new insightful information regarding the integration of mTOR and GJ to regulate spermatogenesis.
Open Access
Microtubule-associated proteins (MAPs) in microtubule cytoskeletal dynamics and spermatogenesis
(Universidad de Murcia, Departamento de Biologia Celular e Histiologia, 2021) Wang, Lingling; Yan, Ming; Wong, Chris K.C.; Ge, Renshan; Wu, Xiaolong; Sun, Fei; Yan Cheng, C.
The microtubule (MT) cytoskeleton in Sertoli cells, a crucial cellular structure in the seminiferous epithelium of adult mammalian testes that supports spermatogenesis, was studied morphologically decades ago. However, its biology, in particular the involving regulatory biomolecules and the underlying mechanism(s) in modulating MT dynamics, are only beginning to be revealed in recent years. This lack of studies in delineating the biology of MT cytoskeletal dynamics undermines other studies in the field, in particular the plausible therapeutic treatment and management of male infertility and fertility since studies have shown that the MT cytoskeleton is one of the prime targets of toxicants. Interestingly, much of the information regarding the function of actin-, MT- and intermediate filament-based cytoskeletons come from studies using toxicant models including some genetic models. During the past several years, there have been some advances in studying the biology of MT cytoskeleton in the testis, and many of these studies were based on the use of pharmaceutical/toxicant models. In this review, we summarize the results of these findings, illustrating the importance of toxicant/pharmaceutical models in unravelling the biology of MT dynamics, in particular the role of microtubule-associated proteins (MAPs), a family of regulatory proteins that modulate MT dynamics but also actin- and intermediate filamentbased cytoskeletons. We also provide a timely hypothetical model which can serve as a guide to design functional experiments to study how the MT cytoskeleton is regulated during spermatogenesis through the use of toxicants and/or pharmaceutical agents.
Open Access
New insights into FAK function and regulation during spermatogenesis
(F. Hernández y Juan F. Madrid. Universidad de Murcia: Departamento de Biología Celular e Histología, 2014) Gungor-Orduer, N. Ece; Mruk, Dolores D.; Wan, Hin-ting; Wong, Elissa W.P.; Celik-Ozenci, Ciler; Lie, Pearl P.Y.; Cheng, C. Yan
Germ cell transport across the seminiferous epithelium during the epithelial cycle is crucial to spermatogenesis, although molecular mechanism(s) that regulate these events remain unknown. Studies have shown that spatiotemporal expression of crucial regulatory proteins during the epithelial cycle represents an efficient and physiologically important mechanism to regulate spermatogenesis without involving de novo synthesis of proteins and/or expression of genes. Herein, we critically review the role of focal adhesion kinase (FAK) in coordinating the transport of spermatids and preleptotene spermatocytes across the epithelium and the blood-testis barrier (BTB), respectively, along the apical ectoplasmic specialization (ES) – blood-testis barrier – basement membrane (BM) functional axis during spermatogenesis. In the testis, p-FAK-Tyr397 and p-FAKTyr407 are spatiotemporally expressed during the epithelial cycle at the actin-rich anchoring junction known as ES, regulating cell adhesion at the Sertolispermatid (apical ES) and Sertoli cell-cell (basal ES) interface. Phosphorylated forms of FAK exert their effects by regulating the homeostasis of F-actin at the ES, mediated via their effects on actin polymerization so that microfilaments are efficiently re-organized, such as from their “bundled” to “de-bundled/branched” configuration and vice versa during the epithelial cycle to facilitate the transport of: (i) spermatids across the epithelium, and (ii) preleptotene spermatocytes across the BTB. In summary, p-FAK-Tyr407 and p-FAK-Tyr397 are important regulators of spermatogenesis which serve as molecular switches that turn “on” and “off” adhesion function at the apical ES and the basal ES/BTB, mediated via their spatiotemporal expression during the epithelial cycle. A hypothetical model depicting the role of these two molecular switches is also proposed.
Open Access
New insights on hormones and factors that modulate Sertoli cell metabolism
(Universidad de Murcia. Departamento de Biología Celular e Histología, 2016) Rato, Luís; Meneses, Maria João; Silva, Branca M.; Sousa, Mário; Alves, Marco G.; Oliveira, Pedro F.
Sertoli cells (SCs) play a key role in spermatogenesis by providing the physical support for developing germ cells and ensuring them the appropriate nutrients, energy sources, hormones, and growth factors. The control of SCs metabolism has been in the spotlight for reproductive biologists, since it may be crucial to determine germ cells’ fate. Indeed, the maintenance of spermatogenesis is highly dependent on the metabolic cooperation established between SCs and germ cells, though this event has been overlooked. It depends on the orchestration of various metabolic pathways and an intricate network of signals. Several factors and/or hormones modulate the metabolic activity of SCs, which are major targets for the hormonal signalling that regulates spermatogenesis. Any alteration in the regulation of these cells’ metabolic behaviour may compromise the normal development of spermatogenesis and consequently, male fertility. In this context, SC metabolism arises as a key regulation point for spermatogenesis. Herein, we present an up-to-date overview on the impact of hormones and factors that modulate SC metabolism, with special focus on glycolytic metabolism, highlighting their relevance in determining male reproductive potential.
Open Access
Regulation of spermatogonial stem cell self-renewal and proliferation in mammals
(Universidad de Murcia, Departamento de Biologia Celular e Histiologia, 2022) Wei, Bang Hong; Hao, Shuang Li; Yang, Wan Xi
The generation of functional sperm relies on spermatogonial stem cells (SSCs) as they can maintain a stem cell pool for continuous generation of functional spermatozoa. The maintenance of SSCs is regulated by several factors. In this paper, we summarize the niche and intrinsic factors in regulating SSC self-renewal and proliferation. GDNF regulates SSC self-renewal through Ras-ERK1/2, SFC, PI3K/Akt and MEK/ERK-mTOR signaling pathways. FGF activates MAPK2K1, ERK and Akt pathways and EGF activates ERK and Akt pathways to induce SSC proliferation. Wnt ligands regulate SSC self-renewal and proliferation through both β-catenin dependent and independent pathways. SCF1 and CXCL12 are also found to have roles in SSC maintenance. As for intrinsic factors in SSCs, ETV5, Bcl6b, Lhx1, ID4 and Nanos2 are regulated by niche factors. They act as the downstream factors of niche factors in regulating SSC self-renewal and proliferation. Transcriptional factors OCT4 and PLZF, as well as FOXO1 in SSCs can directly regulate SSC self-renewal and proliferation. Although we have identified the factors, the detailed mechanism of these factors in regulating SSC fate determination is largely unknown. Here, we summarize factors which have roles in SSC fate determination and hope it will be beneficial for further study and treatment of male infertility.
Open Access
Steroid receptors in the testis: implications in the physiology of prenatal and postnatal development and translation to clinical application
(Universidad de Murcia. Departamento de Biología Celular e Histología, 2023) Rey, Rodolfo A.
The testes are the main source of sex steroids in the male, especially androgens and to a lesser extent estrogens. In target cells, steroid hormones typically signal after binding to intracellular receptors, which act as transcription factors. Androgens and estrogens have ubiquitous functions in peripheral organs, but also have paracrine actions within the gonads where they are far more concentrated. The levels of steroid production by the testes vary throughout fetal and postnatal development: they are high in intrauterine life and in the first months after birth, then they decline and are almost undetectable in childhood and increase again during puberty to attain adult levels. The expression of the androgen and estrogen receptors also depict specific ontogenies in the various testicular cell types. The combination of intratesticular steroid concentration with the pattern of expression of the steroid hormone receptors defines androgen and estrogen action on Sertoli, germ and Leydig cells. Here, we review the ontogeny of expression of the androgen and estrogen receptors in the testis, its impact on testicular physiology during prenatal and postnatal development, as well as its implication on the pathophysiology of different disorders affecting gonadal function throughout life.
Open Access
Testicular cryopreservation: From technical aspects to practical applications
(Universidad de Murcia, Departamento de Biologia Celular e Histiologia, 2025) Pereira, Ana Glória; Matos, Tayná Moura; Albuquerque, Joana Letícia Cottin de; Silva, Andréia Maria da; Silva, Alexandre Rodrigues; Biología Celular e Histología
Testicular cryopreservation has been highlighted as a promising alternative for preserving male fertility and can be applied to restore spermatogenesis in prepubertal individuals or cancer patients, preserve biologically valuable genotypes, and in studies on reproductive physiology or toxicity of various substances. This review presents an analysis of the technical aspects and applications of testicular cryopreservation, examining the contributions of important studies in this area and discussing the different factors that can impact the efficiency of the technique. Testicular fragments can be obtained from living or dead individuals, at any age and reproductive stage, through orchiectomy or biopsy. Among the methods used for processing, slow freezing and vitrification in open or closed systems stand out. However, factors such as species, age, medium used, cryoprotectants, and cryopreservation method can influence the viability of the testis after heating. To obtain sperm, the testes can be cultured in vitro or in vivo and the recovered gametes applied in assisted reproduction techniques. However, in some species, mainly wild animals and humans, this is still a limitation to be overcome.
Open Access
The PI3K/AKT signaling pathway: How does it regulate development of Sertoli cells and spermatogenic cells?
(Universidad de Murcia, Departamento de Biologia Celular e Histiologia, 2022) Chen, Kuang Qi; Wei, Bang Hong; Hao, Shuang Li; Yang, Wan Xi
The PI3K/AKT signaling pathway is one of the most crucial regulatory mechanisms in animal cells, which can mainly regulate proliferation, survival and anti-apoptosis in cell lines. In the seminiferous epithelium, most studies were concentrated on the role of PI3K/AKT signaling in immature Sertoli cells (SCs) and spermatogonia stem cells (SSCs). PI3K/AKT signaling can facilitate the proliferation and antiapoptosis of immature Sertoli cells and spermatogenic cells. Besides, in mature Sertoli cells, this pathway can disintegrate the structure of the blood-testis barrier (BTB) via regulatory protein synthesis and the cytoskeleton of Sertoli cells. All of these effects can directly and indirectly maintain and promote spermatogenesis in male testis.
Open Access
Valproic acid during pregnancy decrease the number of spermatogenic cells and testicular volume in the offspring of mice: Stereological quantification
(Universidad de Murcia, Departamento de Biologia Celular e Histiologia, 2021) Conei, Daniel; Rojas, Mariana; Santamaría, Luis; Risopatrón, Jennie
Valproic acid (VPA) is a drug used to treat epilepsy, bipolar disorders and headaches. As a secondary effect, this antiepileptic drug can cause a decrease in androgens and gonadotropins, and dosedependent testicular defects, such as reduction of testicular weights, sperm motility and degeneration of the seminiferous tubules. In offspring exposed to VPA, its effects have not been evaluated, so the study aimed to determine the morphological effects of the use of VPA along testicular development in mice. 30 adult female BALB/c mice were crossed and divided by age, with embryos of 12.5 days post coitum (dpc), fetuses of 17.5 dpc and male mice 6 weeks postnatal. In each case, the pregnant mouse received 600 mg/kg of VPA, making up the VPA groups, or 0.3 mL of 0.9% physiological solution for the control groups, from the beginning to the end of the pregnancy, orally.t. A morpho-quantitative analysis was carried out on the gonadal development of the male offspring. In the groups treated with VPA, at all ages studied they had lower testicular volume. At 12.5 dpc, they showed less testicular development in the form of sex cords, with fewer gonocytes and somatic cells. At 17.5 dpc, they presented greater interstitial space, fewer spermatogonial, sustentacular Sertoli, peritubular and interstitial Leydig cells. At 6 weeks postnatal, they presented fewer spermatogonia, pachytene spermatocytes, elongated spermatids, sustentacular Sertoli and interstitial Leydig cells, with statistically significant differences. In conclusion, prenatal exposure to VPA causes histopathological alterations in the offspring of mice in testicular development, from the embryonic stage to 6 weeks postnatal.
Open Access
What are the germ cell phenotypes from infertile men telling us about spermatogenesis?
(Murcia : F. Hernández, 1999) Escalier, D.
Drosophila mutants for known genes and those obtained following germline genetic engineering in mice have led to the identification of genes involved in the initiation and the maintenance of spermatogenesis and in the different steps of meiosis. Mutants allow the definition of meiosis-specific checkpoint controls that ensure the transmission of complete and undamaged genetic information. They reveal what spermatogenesis events are interdependent. In the light of these data, an attempt is made to define which events of spermatogenesis could be defective in some well-defined human spermatogenesis failures. They appear to be good models to study the decouplages of spermatogenesis events, the morphogenetic relationships between germ cell structures and the occurrence of pleiotropic sperm phenotypes. It is discussed whether a germ cell with a normal phenotype can transmit a non-functional gene involved in spermatogenesis and how homologous genes can lead to different germ cell phenotypes depending on the species.

Browsing by Subject "Spermatogenesis"

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