title: Transport of germ cells across the seminiferous epithelium during spermatogenesis-the involvement of both actin- and microtubule-based cytoskeletons.
abstract: The transport of germ cells from the base of the seminiferous epithelium toward the luminal edge of the tubule lumen in the adluminal compartment during the epithelial cycle is an essential cellular event to support spermatogenesis. Thus, fully developed elongated spermatids (i.e., spermatozoa) can be released at spermiation in late stage VIII in rodentsversuslate stage II in humans. Earlier studies to examine the molecular mechanism(s) that support germ cell transport, most notably the transport of preleptotene spermatocytes across the blood-testis barrier (BTB), and the transport of elongating spermatids across the adluminal compartment during spermiogenesis, is focused on the adhesion protein complexes at the cell-cell interface. It is generally accepted that cell junctions at the Sertoli cell-cell interface at the BTB, including the actin-based tight junction (TJ), basal ectoplasmic specialization (basal ES, a testis-specific adherens junction) and gap junction (GJ), as well as the intermediate filament-based desmosome undergo constant remodeling to accommodate the transport of preleptotene spermatocytes across the barrier. On the other hand, similar junction dynamics (i.e., disassembly, reassembly and stabilization/maintenance) take place at the Sertoli-spermatid interface. Emerging evidence has shown that junction dynamics at the Sertoli cell-cellvs.Sertoli-germ cell interface are supported by the 2 intriguingly coordinated cytoskeletons, namely the F-actin- and microtubule (MT)-based cytoskeletons. Herein, we provide a brief summary and critically evaluate the recent findings. We also provide an updated hypothetical concept regarding germ cell transport in the testis utilizing the MT-conferred tracks and the MT-specific motor proteins. Furthermore, this cellular event is also supported by the F-actin-based cytoskeleton.
authors.affiliation: The Mary M. Wohlford Laboratory for Male Contraceptive Research, Center for Biomedical Research, Population Council , New York, NY, USA.
authors.forename: Qing
authors.initials: Q
authors.lastname: Wen
authors.affiliation: The Mary M. Wohlford Laboratory for Male Contraceptive Research, Center for Biomedical Research, Population Council , New York, NY, USA.
authors.forename: Elizabeth I
authors.initials: EI
authors.lastname: Tang
authors.affiliation: The Mary M. Wohlford Laboratory for Male Contraceptive Research, Center for Biomedical Research, Population Council, New York, NY, USA; Department of Reproductive Physiology, Zhejiang Academy of Medical Sciences, Hangzhou, China.
authors.forename: Xiang
authors.initials: X
authors.lastname: Xiao
authors.affiliation: The Mary M. Wohlford Laboratory for Male Contraceptive Research, Center for Biomedical Research, Population Council , New York, NY, USA.
authors.forename: Ying
authors.initials: Y
authors.lastname: Gao
authors.affiliation: The Mary M. Wohlford Laboratory for Male Contraceptive Research, Center for Biomedical Research, Population Council , New York, NY, USA.
authors.forename: Darren S
authors.initials: DS
authors.lastname: Chu
authors.affiliation: The Mary M. Wohlford Laboratory for Male Contraceptive Research, Center for Biomedical Research, Population Council , New York, NY, USA.
authors.forename: Dolores D
authors.initials: DD
authors.lastname: Mruk
authors.affiliation: S.B.M. Pharmaceuticals , Rome, Italy.
authors.forename: Bruno
authors.initials: B
authors.lastname: Silvestrini
authors.affiliation: The Mary M. Wohlford Laboratory for Male Contraceptive Research, Center for Biomedical Research, Population Council , New York, NY, USA.
authors.forename: C Yan
authors.initials: CY
authors.lastname: Cheng
mesh_terms: D008841:Actin Cytoskeleton / Q000378:metabolism*; D000818:Animals; D001814:Blood-Testis Barrier; D006801:Humans; D008297:Male; D008870:Microtubules / Q000378:metabolism*; D012670:Seminiferous Epithelium / Q000166:cytology* / Q000378:metabolism; D013091:Spermatogenesis; D013093:Spermatogonia / Q000166:cytology / Q000378:metabolism* / Q000502:physiology
keywords: Sertoli cells; Testis; actin-based cytoskeleton; blood-testis barrier; ectoplasmic specialization; germ cells; microtubule-based cytoskeleton; seminiferous epithelial cycle; spermatogenesis