Archive for the 'Spermatogenesis' Category

07 Apr

Germ Cell Genotype Controls Cell Cycle during Spermatogenesis in the Rat: DISCUSSION(3)

This varies among species and, therefore, shows little conservation during evolution of individual species from common ancestors. Mouse and rat diverged 10-11 million years ago, and now spermatogenesis takes 50% longer in the rat than in the mouse. The second characteristic is that within a species, the cell cycles of the differentiating cells are unalterable. […]

06 Apr

Germ Cell Genotype Controls Cell Cycle during Spermatogenesis in the Rat: DISCUSSION(2)

In the rat, there are believed to be 12 cell divisions leading from stem cell to mature spermatozoa, which is more than for other self-renewing tissues in the body. Furthermore, male germ cell meiosis and morphological changes associated with spermatozoa shaping introduce a complexity to this process not present in other self-renewing tissues. Perhaps this […]

05 Apr

Germ Cell Genotype Controls Cell Cycle during Spermatogenesis in the Rat: DISCUSSION(1)

The results demonstrate that rat spermatogenesis in mouse seminiferous tubules proceeds with cell cycles characteristic of rat germ cells. Although rat germ cells arising from transplanted stem cells are supported by and associated with only mouse Sertoli cells; Fig. 4), their cell cycle is unaltered. This is a remarkable finding considering the close membrane association […]

04 Apr

Germ Cell Genotype Controls Cell Cycle during Spermatogenesis in the Rat: RESULTS(2)

This cell association was identified as rat spermatogenesis because of the presence of 1) elongated spermatids with a shape characteristic of the rat and 2) round spermatids in which mitochondria were at the periphery of the cell. Rat spermatogenesis is distinguished by the alignment of mitochondria along the periphery of the round spermatids, a feature […]

03 Apr

Germ Cell Genotype Controls Cell Cycle during Spermatogenesis in the Rat: RESULTS(1)

The general pattern of donor cell colonization for all 8 recipient mice was similar. Testis tissue examined in xenogeneic transplants showed tubules containing both mouse and rat spermatogenesis. Regardless of whether rat or rat plus mouse donor cells were used, testes showed prominent rat spermatogenesis. Intermingling of rat and mouse germ cells in a single […]

02 Apr

Germ Cell Genotype Controls Cell Cycle during Spermatogenesis in the Rat: MATERIALS AND METHODS(4)

The criteria used to identify rat and mouse spermatogenesis in autoradiographs from mouse recipients were morphological and were four in number. 1) Mitochondrial position in round spermatids of the rat and mouse differed, and this difference could be detected by both light and electron microscopy. By electron microscopy, mitochondria have been shown to remain randomly […]

01 Apr

Germ Cell Genotype Controls Cell Cycle during Spermatogenesis in the Rat: MATERIALS AND METHODS(3)

Testis tissue was embedded in plastic resin (Araldite CY212; Ladd Research Industries, Burlington, VT) and sectioned at 1-^m thickness for microscopic examination. Cells were considered labeled when five or more grains were present over the nucleus or within 1 of the nucleus in the presence of low-to-moderate background. The staging criteria of Leblond and Clermont […]

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