Testicular Regulation in Nonmammalian Vertebrates

Callard, İan P.; Callard, Gloria V.; Lance, Valentine A.; Bolaffi, Janice L.; Rosset, Jill S.

doi:10.1095/biolreprod18.1.16

Cited by 99 publications

(21 citation statements)

References 171 publications

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“…In comparison to R. catesbeiana observed in the present study, Kalt 2 and Callard et al 6 have studied testes of male X. laevis and found 11 stages of germ cells. They employed H 3 -thymidine labelling and calculated the durations of various cell stages, including leptotene, zygotene, pachytene, diplotene and metaphase spermatocytes, whose durations were found to be 4, 6, 12, 1 and 1 days, respectively; and spermiogenesis needed 12 days to complete the process.…”

Section: Germ Cell Classificationcontrasting

confidence: 41%

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Chavadej¹,

Jerareungrattana²,

Sretarugsa³

et al. 2000

ScienceAsia

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The testes of fully mature bullfrogs, Rana catesbeiana, were studied by light microscope. The germ cells in the developing testis can be classified into 12 stages based on nuclear characteristics. Primary(type A) and secondary(type B) spermatogonia are the earliest germ cells, with the former showing large and completely euchromatic nuclei with prominent nucleoli and the latter with small blocks of heterochromatin distributed along the nuclear envelope. Spermatocytes consist of five stages; namely, leptotene, zygotene, pachytene, diplotene and diakinesis metaphase spermatocytes. Succeeding stages show increasing condensation of chromatin : from the coarse fibers, that are evenly distributed throughout the nucleus in leptotene stage to the highly condensed blocks of heterochromatin in pachytene and diplotene stages. Nucleoli are not detected in any stages. Secondary spermatocytes have blocks of completely condensed heterochromatin attaching to the nuclear envelopes. There are three stages of spermatids: the early stage shows coarse chromatin granules occurs evenly over the nucleus, the middle stage has increased chromatin condensation over the entire oval nucleus while the nuclear size decreases. The late stage exhibits completely condensed chromatin in an elongated nucleus, and its cytoplasm becomes highly vacuolized and starts to degenerate. In fully mature spermatozoa, the nucleus becomes highly elongated and chromatin completely condensed. During development of the testis, sex cords in putative testis appear in two-month-old frogs. Seminiferous tubules containing primary spermatogonia appear in the definitive testis of four-month-old frogs while spermatocytes are present in five-monthold frogs. Spermiogenesis and full production of spermatozoa could be detected from the seventh month onwards. The frogs become fully mature about sixteen months when their testes undergo cyclical change. During breeding period (April-September), there are abundant spermatozoa, round spermatids in seminiferous tubules, while during non-breeding period (October-March), such cells are much fewer in number and most remaining cells are spermatogonia and primary spermatocytes.

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Section: Germ Cell Classificationcontrasting

confidence: 41%

Untitled

Chavadej¹,

Jerareungrattana²,

Sretarugsa³

et al. 2000

ScienceAsia

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“…There is no capsule, collagen membrane or fibroblasts delimiting the cellular aggregation, as can be seen in Figure 6 of the sample stained with Masson's Trichrome. There are studies in fishes and amphibians that demonstrate the formation of cysts in the seminiferous epithelium, however the spermatogenic process is different, all of the spermatogenesis stages occur in the cysts, until breaking during spermiation (Callard et al 1978).…”

Section: Resultsmentioning

confidence: 99%

Aspects of spermatogenesis and microscopic testicular morphology in Greater Rhea, Rhea americana (Linnaeus, 1758)

2016

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ABSTRACT.-Freneau G.E., Carvalho S.F.M., Saboia-Morais S.M. T. & Freneau B.N. 2016 The purpose of this study was to study the microscopic morphology of the testicular parenchyma of Rhea americana birds. Fifty-four 2.5±0.5 year-old male adults bred in captivity. were used. During commercial slaughter, samples of testis were collected in November respectively. Microscopic measures of seminiferous tubules, spermatic cells and diameter of the nuclei were presented. These data confirm reproductive seasonality, with breeding season in spring-summer with sperm production. A great variation n parenchyma, when compared breeding was noticeable.

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“…Some of the articles related to soft-shelled turtles have focused on their reproductive cycles, descriptions of the annual changes in their steroidogenic activity, and on the gross morphology of the testis (Callard and Hirsch, 1976;Lofts and Calaby, 1977;Callard et al, 1978;Moll, 1979;Licht et al, 1985). The male and female reproductive cycles are not synchronized in temperate zone turtles, which results in the production of their respective gametes at different times of the year (Licht, 1984;Chen et al, 2006).…”

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confidence: 99%

Spermiogenesis in Soft‐Shelled Turtle, Pelodiscus sinensis

Zhang

Han

et al. 2007

The Anatomical Record

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Spermiogenesis in the soft-shelled turtle, Pelodiscus sinensis, was examined by transmission electron microscopy. The process includes nuclear elongation, chromatin condensation, acrosomal and flagellar development, and elimination of excess cytoplasm. In stage I, the proacrosomal vesicle occurs next to a shallow fossa of the nucleus, and a dense acrosomal granule forms beneath it. A smaller subacrosomal granule in the middle of the fibrous layer is related to the development of intranuclear tubules. The nucleus begins to move eccentrically. In stage II, the round proacrosomal vesicle is flattened by protrusion of the nuclear fossa, and the dense acrosomal granule diffuses into the vesicle, as the fibrous layer forms the subacrosomal cone. Circular manchettes develop around the nucleus, and the chromatin coagulates into small granules. The movement of the nucleus causes rearrangement of the cytoplasm. In stage III, the front of the elongating nucleus protrudes out of the spermatid and is covered by the flat acrosome; coarse granules replace the small ones within the nucleus. At the posterior pole of the head, mitochondria move backward. Numerous microtubules begin to assemble the axoneme of flagellum. In stage IV, the chromatin concentrates to dense homogeneous phase. The circular manchette is reorganized longitudinally. The Sertoli process covers the acrosome and the residues of the cytoplasmic lobes are eliminated. In stage V, the sperm head matures. After dissolution of the longitudinal manchette, the mitochondria arrange themselves around the proximal and distal centrioles. Caudal to the mitochondrial mass, a fibrous sheath surrounds the proximal portion of the flagellum. Anat Rec,

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Testicular Regulation in Nonmammalian Vertebrates

Cited by 99 publications

References 171 publications

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Aspects of spermatogenesis and microscopic testicular morphology in Greater Rhea, Rhea americana (Linnaeus, 1758)

Spermiogenesis in Soft‐Shelled Turtle, Pelodiscus sinensis

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