Spermatogenesis最新文献

{"title":"Ultrastructure of spermatid development within the testis of the Yellow-Bellied Sea Snake, Pelamis platurus (Squamata: Elapidae)","authors":"K. Gribbins, Layla R. Freeborn, D. Sever","doi":"10.1080/21565562.2016.1261666","DOIUrl":"https://doi.org/10.1080/21565562.2016.1261666","url":null,"abstract":"ABSTRACT Little is known about spermatid development during spermiogenesis in snakes, as there is only one complete study in ophidians, which details the spermatid ultrastructure within the viperid, Agkistrodon piscivorus. Thus, the following study will add to our understanding of the ontogenic steps of spermiogenesis in snakes by examining spermatid maturation in the elapid, Pelamis platurus, which were collected in Costa Rica in 2009. The spermatids of P. platurus share many similar ultrastructural characteristics to that described for other squamates during spermiogenesis. Three notable differences between the spermatids of P. platurus and those of other snakes is a round and shorter epinuclear lucent zone, enlarged caudal nuclear shoulders, and more prominent 3 and 8 peripheral fibers in the principal and endpieces. Also, the midpiece is much longer in P. platurus and is similar to that reported for all snakes studied to date. Other features of chromatin condensation and morphology of the acrosome complex are similar to what has been observed in A. piscivorus and other squamates. Though the spermatids in P. platurus appear to be quite similar to other snakes and lizards studied to date, some differences in subcellular details are still observed. Analysis of developing spermatids in P. platurus and other snakes could reveals morphologically conserved traits between different species along with subtle changes that could help determine phylogenetic relationships once a suitable number of species have been examined for ophidians and other squamates.","PeriodicalId":22074,"journal":{"name":"Spermatogenesis","volume":"87 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2016-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77488821","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Polycomb-dependent nucleolus localization of Jumonji/Jarid2 during Drosophila spermatogenesis","authors":"M. Goto, Narumi Toda, Kouhei Shimaji, Dang Ngoc Anh Suong, Nicole Vo, H. Kimura, H. Yoshida, Y. Inoue, M. Yamaguchi","doi":"10.1080/21565562.2016.1232023","DOIUrl":"https://doi.org/10.1080/21565562.2016.1232023","url":null,"abstract":"ABSTRACT Drosophila Jumonji/Jarid2 (dJmj) has been identified as a component of Polycomb repressive complex 2. However, it is suggested that dJmj has both PRC-dependent and –independent roles. Subcellular localization of dJmj during spermatogenesis is unknown. We therefore performed immunocytochemical analyses with specific antibodies to dJmj and tri-methylation at lysine 27 on histone H3 (H3K27me3). Interestingly, dJmj exclusively localizes at nucleolus in the late growth stage. Examination of the dJmj localization in various Polycomb group (PcG) mutant lines at the late growth stage allowed identification of some PcG genes, including Polycomb (Pc), to be responsible for dJmj recruitment to nucleolus. In addition, we found that size of nucleolus was decreased in some of these mutant lines. In a mutant of testis-specific TAF homolog (tTAF) that is responsible for nucleolus localization of Pc, dJmj signals were detected not only at nucleolus but also on the condensed chromatin in the late growth stage. Duolink In situ Proximity ligation assay clarified that Pc interacts with dJmj at nucleolus in the late growth stage. Furthermore, the level of H3K27me3 decreased in nuclei at this stage. Taken together, we conclude that tTAF is responsible for recruitments of dJmj to nucleolus in the late growth stage that appears to be mediated by Pc. Compartmentalization of dJmj in nucleolus together with some of PcG may be necessary to de-repress the expression of genes required to cellular growth and proliferation in the following meiotic divisions.","PeriodicalId":22074,"journal":{"name":"Spermatogenesis","volume":"34 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2016-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80649671","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Overexpression of plastin 3 in Sertoli cells disrupts actin microfilament bundle homeostasis and perturbs the tight junction barrier.","authors":"Nan Li,&nbsp;Will M Lee,&nbsp;C Yan Cheng","doi":"10.1080/21565562.2016.1206353","DOIUrl":"https://doi.org/10.1080/21565562.2016.1206353","url":null,"abstract":"<p><p>Throughout the epithelial cycle of spermatogenesis, actin microfilaments arranged as bundles near the Sertoli cell plasma membrane at the Sertoli cell-cell interface that constitute the blood-testis barrier (BTB) undergo extensive re-organization by converting between bundled and unbundled/branched configuration to give plasticity to the F-actin network. This is crucial to accommodate the transport of preleptotene spermatocytes across the BTB. Herein, we sought to examine changes in the actin microfilament organization at the Sertoli cell BTB using an in vitro model since Sertoli cells cultured in vitro is known to establish a functional tight junction (TJ)-permeability barrier that mimics the BTB in vivo. Plastin 3, a known actin microfilament cross-linker and bundling protein, when overexpressed in Sertoli cells using a mammalian expression vector pCI-neo was found to perturb the Sertoli cell TJ-barrier function even though its overexpression increased the overall actin bundling activity in these cells. Furthermore, plastin 3 overexpression also perturbed the localization and distribution of BTB-associated proteins, such as occludin-ZO1 and N-cadherin-β-catenin, this thus destabilized the barrier function. Collectively, these data illustrate that a delicate balance of actin microfilaments between organized in bundles vs. an unbundled/branched configuration is crucial to confer the homeostasis of the BTB and its integrity. </p>","PeriodicalId":22074,"journal":{"name":"Spermatogenesis","volume":"6 1","pages":"e1206353"},"PeriodicalIF":0.0,"publicationDate":"2016-06-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/21565562.2016.1206353","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"34389311","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Letter from the Editor","authors":"C. Cheng","doi":"10.1080/21565562.2016.1216689","DOIUrl":"https://doi.org/10.1080/21565562.2016.1216689","url":null,"abstract":"This is the second issue of volume 6 of Spermatogenesis since we first launched our journal back in January 2011. While six years do not seem like a very long time for a scientific journal, we have witnessed rapid changes and advancement in the field these past years, even amidst budget constraints in many laboratories across the globe due to cutback from funding agencies. However, these setbacks have actually helped investigators to become more focused in their studies, using limited budgets and resources in the laboratory to perform innovative studies with better designed experiments, while also trying to relate research studies to diseases and/or improving human health, such as treating infertility in men. Furthermore, we have also seen technological advances in all fronts and the development of multiple animal models to study spermatogenesis, besides the traditional gene knock-out or knock-in models. For instance, we have seen exciting advances in the culture of human undifferentiated spermatogonia or rodent spermatogonial stem cells into functional spermatids. This important technological advance can likely be used in the near future for in vitro fertilization to help infertile men with nonobstructive azoospermia to father their own children. During these past six years, Spermatogenesis has published several very well-received special issues, which include “Drosophila Spermatogenesis,” “Testicular Toxicity,” and “Spermatogenesis in Non-Mammalian and Vertebrates.” These issues were edited by leading senior investigators in the field, and the contributors were active and leading investigators. These issues will remain as important sources of references for investigators in the years to come. We are also grateful to many of the board members and readers of our journal who contribute to the journal’s growth by publishing some of their best work in Spermatogenesis. We will continue to do our best to maintain the quality of our journal, and I encourage scientists and readers, including our board members, to consider Spermatogenesis to publish your data, innovative techniques, ideas, thoughts, and concepts in the coming issues. I also welcome ideas and suggestions to further improve our journal, with which you can e-mail me at y-cheng@popcbr.rockefeller.edu. Furthermore, I also want to thank our journal staff, in particular Ms. Karen Benskin, our Managing Editor; Ms. Megan Hein, our Production Editor; and Mr. Zachary Ayres, our Peer Review Systems Coordinator, all of whom have worked relentlessly hard to maintain the quality of our journal in the past year. I am also grateful that I can be part of this professional team to serve the readers of Spermatogenesis.","PeriodicalId":22074,"journal":{"name":"Spermatogenesis","volume":"28 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2016-05-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77824034","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Does cell polarity matter during spermatogenesis?","authors":"Ying Gao, C. Cheng","doi":"10.1080/21565562.2016.1218408","DOIUrl":"https://doi.org/10.1080/21565562.2016.1218408","url":null,"abstract":"ABSTRACT Cell polarity is crucial to development since apico-basal polarity conferred by the 3 polarity protein modules (or complexes) is essential during embryogenesis, namely the Par (partition defective)-, the CRB (Crumbs)-, and the Scribble-based polarity protein modules. While these protein complexes and their component proteins have been extensively studied in Drosophila and C. elegans and also other mammalian tissues and/or cells, their presence and physiological significance in the testis remain unexplored until the first paper on the Par-based protein published in 2008. Since then, the Par-, the Scribble- and the CRB-based protein complexes and their component proteins in the testis have been studied. These proteins are known to confer Sertoli and spermatid polarity in the seminiferous epithelium, and they are also integrated components of the tight junction (TJ) and the basal ectoplasmic specialization (ES) at the Sertoli cell-cell interface near the basement membrane, which in turn constitute the blood-testis barrier (BTB). These proteins are also found at the apical ES at the Sertoli-spermatid interface. Thus, these polarity proteins also play a significant role in regulating Sertoli and spermatid adhesion in the testis through their actions on actin-based cytoskeletal function. Recent studies have shown that these polarity proteins are having antagonistic effects on the BTB integrity in which the Par6- and CRB3-based polarity complexes promotes the integrity of the Sertoli cell TJ-permeability barrier, whereas the Scribble-based complex promotes restructuring/remodeling of the Sertoli TJ-barrier function. Herein, we carefully evaluate these findings and provide a hypothetic model regarding their role in the testis in the context of the functions of these polarity proteins in other epithelia, so that better experiments can be designed in future studies to explore their significance in spermatogenesis.","PeriodicalId":22074,"journal":{"name":"Spermatogenesis","volume":"47 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2016-05-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89314402","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Genomic and expression analysis of transition proteins in Drosophila.","authors":"Zain A Alvi, Tin-Chun Chu, Valerie Schawaroch, Angela V Klaus","doi":"10.1080/21565562.2016.1178518","DOIUrl":"10.1080/21565562.2016.1178518","url":null,"abstract":"<p><p>The current study was aimed at analyzing putative protein sequences of the transition protein-like proteins in 12 Drosophila species based on the reference sequences of transition protein-like protein (Tpl (94D) ) expressed in Drosophila melanogaster sperm nuclei. Transition proteins aid in transforming chromatin from a histone-based nucleosome structure to a protamine-based structure during spermiogenesis - the post-meiotic stage of spermatogenesis. Sequences were obtained from NCBI Ref-Seq database using NCBI ORF-Finder (PSI-BLAST). Sequence alignments and analysis of the amino acid content indicate that orthologs for Tpl (94D) are present in the melanogaster species subgroup (D. simulans, D. sechellia, D. erecta, and D. yakuba), D. ananassae, and D. pseudoobscura, but absent in D. persmilis, D. willistoni, D. mojavensis, D. virilis, and D. grimshawi. Transcriptome next generation sequence (RNA-Seq) data for testes and ovaries was used to conduct differential gene expression analysis for Tpl (94D) in D. melanogaster, D. simulans, D. yakuba, D. ananassae, and D. pseudoobscura. The identified Tpl (94D) orthologs show high expression in the testes as compared to the ovaries. Additionally, 2 isoforms of Tpl (94D) were detected in D. melanogaster with isoform A being much more highly expressed than isoform B. Functional analyses of the conserved region revealed that the same high mobility group (HMG) box/DNA binding region is conserved for both Drosophila Tpl (94D) and Drosophila protamine-like proteins (MST35Ba and MST35Bb). Based on the rigorous bioinformatic approach and the conservation of the HMG box reported in this work, we suggest that the Drosophila Tpl (94D) orthologs should be classified as their own transition protein group. </p>","PeriodicalId":22074,"journal":{"name":"Spermatogenesis","volume":"5 3","pages":"e1178518"},"PeriodicalIF":0.0,"publicationDate":"2016-04-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4964972/pdf/kspe-05-03-1178518.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"34653368","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Formins: Actin nucleators that regulate cytoskeletal dynamics during spermatogenesis.","authors":"Nan Li,&nbsp;Dolores D Mruk,&nbsp;Elizabeth I Tang,&nbsp;Chris Kc Wong,&nbsp;Will M Lee,&nbsp;Bruno Silvestrini,&nbsp;C Yan Cheng","doi":"10.1080/21565562.2015.1066476","DOIUrl":"https://doi.org/10.1080/21565562.2015.1066476","url":null,"abstract":"<p><p>Formins are a growing class of actin nucleation proteins that promote the polymerization of actin microfilaments, forming long stretches of actin microfilaments to confer actin filament bundling in mammalian cells. As such, microfilament bundles can be formed in specific cellular domains, in particular in motile mammalian cells, such as filopodia. Since ectoplasmic specialization (ES), a testis-specific adherens junction (AJ), at the Sertoli cell-cell and Sertoli-spermatid interface is constituted by arrays of actin microfilament bundles, it is likely that formins are playing a significant physiological role on the homeostasis of ES during the epithelial cycle of spermatogenesis. In this Commentary, we provide a timely discussion on formin 1 which was recently shown to be a crucial regulator of actin microfilaments at the ES in the rat testis (Li N et al. <i>Endocrinology</i>, 2015, <i>in press</i>; DOI: 10.1210/en.2015-1161, PMID:25901598). We also highlight research that is needed to unravel the functional significance of formins in spermatogenesis.</p>","PeriodicalId":22074,"journal":{"name":"Spermatogenesis","volume":"5 2","pages":"e1066476"},"PeriodicalIF":0.0,"publicationDate":"2015-06-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/21565562.2015.1066476","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"34041485","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Separating from the pack: Molecular mechanisms of <i>Drosophila</i> spermatid individualization.","authors":"Josefa Steinhauer","doi":"10.1080/21565562.2015.1041345","DOIUrl":"https://doi.org/10.1080/21565562.2015.1041345","url":null,"abstract":"Successful completion of gametogenesis is critical for perpetuation of the species. In addition to the inherent interest, studies of gamete development, in particular spermatogenesis, have yielded insight into diverse biological processes, including actin and microtubule organization, mitochondrial dynamics, plasma membrane remodeling, lipid signaling, apoptosis, and many others. Mammalian sperm are formed from germline stem cells that reside near the basal surface of the seminiferous tubules. Spermatogonia produced from these stem cells undergo amplifying mitotic divisions with incomplete cytokinesis to eventually produce interconnected chains of spermatocytes that synchronously transition into meiosis. Cytokinesis of the meiotic divisions also is incomplete, such that cytoplasmic channels remain between sister spermatids after each division. This allows for the sharing of cytoplasm between sister spematids, which synchronizes their development and protects them from the genetic effects of haploidy. Following meiosis, the haploid spermatids undergo spermiogenesis, the terminal differentiation process wherein acrosomes are formed from Golgi, chromatin compacts, the nuclei are reshaped, and the flagella elongate. After terminal differentiation, the cytoplasmic contents are removed and the cytoplasmic bridges connecting sister spermatozoa are dissolved. 10 This last process is dependent on the actin cytoskeleton and is essential for proper sperm function. The spermatozoa are released from the testis into the epididymis, where their plasma membranes undergo molecular changes. Epididymal activation is required for motility and fertilization. Spermatogenesis is strikingly similar in the fruit fly, and many molecular players are conserved between mammals and Drosophila. A single Drosophila gonialblast, formed by division of a germline stem cell, undergoes four mitotic divisions and two meiotic divisions to produce 64 interconnected sister spermatids in a germline cyst. As in mammals, incomplete cytokinesis leads to cytoplasmic sharing between sister spermatids, via intercellular bridges called ring canals. Following nuclear compaction and formation of the flagella, the interspermatid bridges are dissolved concurrently with cytoplasm removal in an actin-dependent process called spermatid individualization. Much has been discovered about this process in the 21 century. Individualization is carried out by the individualization complex (IC), which first forms at the rostral end of the cyst, around the spermatid nuclei (Figure 1). The IC is composed of 64 actin cones, one for each germ nucleus of the cyst. Actin filaments form a meshwork at the leading edge of the cones and are organized into parallel bundles at the rear of the cones. The meshwork is formed by the Arp2/3 actin nucleating complex. The actin motor Myosin VI works with unknown binding partners to localize Arp2/3 and to stabilize the meshwork at the front of the cones. Other factors at the cone","PeriodicalId":22074,"journal":{"name":"Spermatogenesis","volume":"5 2","pages":"e1041345"},"PeriodicalIF":0.0,"publicationDate":"2015-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/21565562.2015.1041345","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"34041483","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Antioxidant protects blood-testis barrier against synchrotron radiation X-ray-induced disruption.","authors":"Tingting Zhang,&nbsp;Tengyuan Liu,&nbsp;Jiaxiang Shao,&nbsp;Caibin Sheng,&nbsp;Yunyi Hong,&nbsp;Weihai Ying,&nbsp;Weiliang Xia","doi":"10.1080/21565562.2015.1009313","DOIUrl":"https://doi.org/10.1080/21565562.2015.1009313","url":null,"abstract":"<p><p>Synchrotron radiation (SR) X-ray has wide biomedical applications including high resolution imaging and brain tumor therapy due to its special properties of high coherence, monochromaticity and high intensity. However, its interaction with biological tissues remains poorly understood. In this study, we used the rat testis as a model to investigate how SR X-ray would induce tissue responses, especially the blood-testis barrier (BTB) because BTB dynamics are critical for spermatogenesis. We irradiated the male gonad with increasing doses of SR X-ray and obtained the testicles 1, 10 and 20 d after the exposures. The testicle weight and seminiferous tubule diameter reduced in a dose- and time-dependent manner. Cryosections of testes were stained with tight junction (TJ) component proteins such as occludin, claudin-11, JAM-A and ZO-1. Morphologically, increasing doses of SR X-ray consistently induced developing germ cell sloughing from the seminiferous tubules, accompanied by shrinkage of the tubules. Interestingly, TJ constituent proteins appeared to be induced by the increasing doses of SR X-ray. Up to 20 d after SR X-ray irradiation, there also appeared to be time-dependent changes on the steady-state level of these protein exhibiting differential patterns at 20-day after exposure, with JAM-A/claudin-11 still being up-regulated whereas occludin/ZO-1 being down-regulated. More importantly, the BTB damage induced by 40 Gy of SR X-ray could be significantly attenuated by antioxidant N-Acetyl-L-Cysteine (NAC) at a dose of 125 mg/kg. Taken together, our studies characterized the changes of TJ component proteins after SR X-ray irradiation, illustrating the possible protective effects of antioxidant NAC to BTB integrity.</p>","PeriodicalId":22074,"journal":{"name":"Spermatogenesis","volume":"5 1","pages":"e1009313"},"PeriodicalIF":0.0,"publicationDate":"2015-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/21565562.2015.1009313","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"34041484","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Testicular structure and germ cells morphology in salamanders.","authors":"Mari Carmen Uribe, Víctor Mejía-Roa","doi":"10.4161/21565562.2014.988090","DOIUrl":"10.4161/21565562.2014.988090","url":null,"abstract":"<p><p>Testes of salamanders or urodeles are paired elongated organs that are attached to the dorsal wall of the body by a mesorchium. The testes are composed of one or several lobes. Each lobe is morphologically and functionally a similar testicular unit. The lobes of the testis are joined by cords covered by a single peritoneal epithelium and subjacent connective tissue. The cords contain spermatogonia. Spermatogonia associate with Sertoli cells to form spermatocysts or cysts. The spermatogenic cells in a cyst undergo their development through spermatogenesis synchronously. The distribution of cysts displays the cephalo-caudal gradient in respect to the stage of spermatogenesis. The formation of cysts at cephalic end of the testis causes their migration along the lobules to the caudal end. Consequently, the disposition in cephalo-caudal regions of spermatogenesis can be observed in longitudinal sections of the testis. The germ cells are spermatogonia, diploid cells with mitotic activity; primary and second spermatocytes characterized by meiotic divisions that develop haploid spermatids; during spermiogenesis the spermatids differentiate to spermatozoa. During spermiation the cysts open and spermatozoa leave the testicular lobules. After spermiation occurs the development of Leydig cells into glandular tissue. This glandular tissue regressed at the end of the reproductive cycle.</p>","PeriodicalId":22074,"journal":{"name":"Spermatogenesis","volume":"4 3","pages":"e988090"},"PeriodicalIF":0.0,"publicationDate":"2015-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4581064/pdf/kspe-04-03-988090.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"34039650","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}