Les �l�ments cytoplasmiques au cours de la spermiogen�se du TritonPleurodeles waltlii Michah

Picheral, Bertrand

doi:10.1007/bf00582856

Cited by 17 publications

(14 citation statements)

References 33 publications

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“…A number of studies have reported on the fine structure of different aspects of spermatogenesis in several species of urodels, e.g., Pleurodeles wnltlii (Picheral, 1967(Picheral, , 1972a(Picheral, ,b,c, 1979; D. fuscus (Lommen, 1970); Salamandra salamandra (Bergmann et al, 1982;Schindelmeiser et al, 1985); Ambystoma mexicanum (Keyhani and Lemanski, 1981;Miltner and Armstrong, 1983).…”

Section: Urodelesmentioning

confidence: 99%

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Spermatogenesis in nonmammalian vertebrates

Pudney

1995

Microscopy Res & Technique

178

120

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Spermatogenesis appears to be a fairly conserved process throughout the vertebrate series. Thus, spermatogonia develop into spermatocytes that undergo meiosis to produce spermatids which enter spermiogenesis where they undergo a morphological transformation into spermatozoa. There is, however, variation amongst the vertebrates in how germ cell development and maturation is accomplished. This difference can be broadly divided into two distinct patterns, one present in anamniotes (fish, amphibia) and the other in amniotes (reptiles, birds, mammals). For anamniotes, spermatogenesis occurs in spermatocysts (cysts) which for most species develop within seminiferous lobules. Cysts are produced when a Sertoli cell becomes associated with a primary spermatogonium. Mitotic divisions of the primary spermatogonium produce a cohort of secondary spermatogonia that are enclosed by the Sertoli cell which forms the wall of the cyst. With spermatogenic progression a clone of isogeneic spermatozoa is produced which are released, by rupture of the cyst, into the lumen of the seminiferous lobule. Following spermiation, the Sertoli cell degenerates. For anamniotes, therefore, there is no permanent germinal epithelium since spermatocysts have to be replaced during successive breeding seasons. By contrast, spermatogenesis in amniotes does not occur in cysts but in seminiferous tubules that possess a permanent population of Sertoli cells and spermatogonia which act as a germ cell reservoir for succeeding bouts of spermatogenic activity. There is, in general, a greater variation in the organization of the testis and pattern of spermatogenesis in the anamniotes compared to amniotes. This is primarily due to the fact there is more reproductive diversity in anamniotes ranging from a relatively unspecialized condition where gametes are simply released into the aqueous environment to highly specialized strategies involving internal fertilization. These differences are obviously reflected in the mode of spermatogenesis and this is particularly true of the stage of spermiogenesis where the morphology of the species-specific spermatozoon is determined. Moreover, unlike amniotes, many anamniotes display a spermatogenic wave manifest, depending upon the species, either at the level of the cyst or seminiferous lobule. This variation in the organization of the testis makes certain anamniotes perfect models for investigating germ cell development and maturation. For instance, the presence of a spermatogenic wave provides an opportunity to manually isolate discrete germ cell stages for analysis of specific Sertoli/germ cell interactions. Furthermore, for many anamniotes, germ cells mature in association with a morphologically poorly developed Sertoli cell. This seeming independence of Sertoli cell regulation allows the in vitro culture of isolated germ cells of some species of anamniotes through several developmental stages. Thus, due either to the anatomical organization of the testis, or structural simplicity of the germinal units, nonmammalian vert...

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Section: Urodelesmentioning

confidence: 99%

“…The fine structure of urodelean spermatozoa has been best studied in P. waltlii (Picheral, 1967(Picheral, , 1972a(Picheral, ,b,c, 1979. The spermatozoa possess an acroso-ma1 cap that ends in either a sharp point or rounded knob and in some species develops a hooked barb, e.g., P. waltlii, Euproctus aspes.…”

Section: Urodelesmentioning

confidence: 99%

Spermatogenesis in nonmammalian vertebrates

Pudney

1995

Microscopy Res & Technique

178

120

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“…The mitochondria were still localized in the region close to the cell membrane, and the acrosome and flagella with rings were present. These results indicated that the morphological changes in organ culture with FSH mimicked those in vivo (21,22).…”

Section: Ultrastructure Of the Testes In The Presence And Absence Of Fshmentioning

confidence: 84%

Differentiation of Primary Spermatocytes to Elongated Spermatids by Mammalian FSH in Organ Culture of Testes Fragments from the Newt, Cynops pyrrhogaster

Ji¹,

Abee²

1994

Dev Growth Differ

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Our previous studies (10, 11) showed that mammalian follicle-stimulating hormone (FSH) alone was indispensable and sufficient for the initiation and promotion of spermatogenesis from secondary spermatogonia to primary spermatocytes in organ culture of testes fragments from the newt, Cynops pyrrhogaster. The present study demonstrated that FSH promoted in the same modet system the differentiation of primary spermatocytes even further: to the stage of elongated spermatids. When testes fragments, consisting of somatic cells and germ cells (mostly primary spermatocytes), were cultured in a control medium for three weeks, only round spermatids and spermatogonia were observed: both the diameter of the cysts and the viability of the germ cells decreased to about 10-15% of the original level. On the other hand, when the medium was supplemented with FSH, elongated spermatids appeared by the second week; both the diameter of the cysts and the viability of the germ cells were maintained at a higher level than in the control medium. The effect of FSH was dose-dependent. However, neither transferrin, androgens (testosterone and 5a-dihydrotestosterone) nor luteinizing hormone (LH) was effective. The addition of cyanoketone, a specific inhibitor of 3,8-hydroxy-d5-steroid dehydrogenase (3p-HSD) (32), to the FSH-containing medium did not prevent the differentiation promoted by FSH, indicating that it is unlikely that d4-steroid metabolites produced in fragments by FSH acted directly on germ cells. Insulin was found to improve the viability of germ cells during a 2 week of culture period. In the presence of FSH, the cells in various differentiative stages had morphological characteristics very similar to those in vivo, whereas in the absence of FSH primary spermatocytes showed abnormal features in their nuclei and cytoplasm, indicating that they were deteriorating. These results and our previous results (1-3) suggest that FSH promotes primary spermatocytes to differentiate intb elongated spermatids probably by stimulating Sertoli cells to secrete factors which then act on the germ cells.

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“…The conical perforatorium appears unlikely to be homologous with either the axial perforatorium and/or subacrosomal cone/periperforatorial material found in urodeles, caecilians and some primitive frogs. The conical perforatorium develops much later in spermiogenesis, in a different position, and with a different ontogeny and final form (Abé et al 1981;Picheral 1972;Folliot 1979;Rastogi et al 1988;Lee and Kwon 1992), and is probably a unique development of those anurans possessing it. However, the replacement of an axially located rod-like perforatorium with a conical, albeit putative, perforatorium, is a synapomorphy whether or not axial and conical perforatoria are homologous.…”

Section: Discussionmentioning

confidence: 99%

Morphology of the spermatozoa of the Microhylidae (Anura, Amphibia)

et al. 2002

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Microhylid spermatozoa show the autapomorphic condition of possessing a thin post‐mitochondrial cytoplasmic collar. Their spermatozoa are apomorphic in several respects. They have lost the distinct nuclear shoulder, endonuclear canal and axial perforatorium observed in urodeles, caecilians and primitive frogs, possess a conical perforatorium and apomorphically lack any fibres associated with the axoneme. The spermatozoa of Cophixalus, however, differ in several respects from those of the other microhylids examined. Cophixalus spermatozoa are longer in almost all measurements, the acrosome vesicle is cylindrical and does not completely cover the putative perforatorium, the perforatorium is asymmetrical and composed of fine fibres, the nucleus is strongly attenuated and narrower, and the mitochondria are elongate. The absence of fibres associated with the axoneme is an apomorphic condition shared with the Ranidae, Rhacophoridae and Pipidae.

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Les �l�ments cytoplasmiques au cours de la spermiogen�se du TritonPleurodeles waltlii Michah

Cited by 17 publications

References 33 publications

Spermatogenesis in nonmammalian vertebrates

Spermatogenesis in nonmammalian vertebrates

Differentiation of Primary Spermatocytes to Elongated Spermatids by Mammalian FSH in Organ Culture of Testes Fragments from the Newt, Cynops pyrrhogaster

Morphology of the spermatozoa of the Microhylidae (Anura, Amphibia)

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