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A primitive male germ cell, the last generation of which gives rise to spermatocytes.



a developing male sexual cell during the period of division prior to growth. Spermatogonia are in a state of rapid mitotic division. Primary and secondary spermatogonia are distinguished in insects and certain other invertebrates; secondary spermatogonia, the smaller of the two types, are surrounded by cells that form the seminal vesicle, or spermatocyst. Mammals have two types of spermatogonia, which differ in degree of differentiation and in chromatinic structure. The duration of the period of division varies from one animal species to another, depending on the number of generations and the rate of division of spermatogonia—parameters that are constant for eachspecies. Spermatogonia are formed in the parietal layer of the seminiferous tubules. Many animals have a specific zone of division in the cecum of the testes.

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Control group Table 3: The number of different testis cell types (x[10.sup.6]) Groups Spermatogonia A Spermatogonia B Sertoli cell Control 0.83[+ or -]0.06 0.16[+ or -]0.07 2.7[+ or -]0.2 BD1/2 0.83[+ or -]0.05 0.13[+ or -]0.05 2.5[+ or -]0.1 BD1/4 0.84[+ or -]0.05 0.18[+ or -]0.05 2.7[+ or -]0.3 Groups Primary Round Long spermatocyte spermatid spermatid Control 12.1[+ or -]0.98 31.8[+ or -]2.49 30.9[+ or -]3.02 BD1/2 12.0[+ or -]0.80 31.0[+ or -]2.18 30.6[+ or -]2.66 BD1/4 12.4[+ or -]0.92 32.2[+ or -]2.20 32.1[+ or -]2.65 Groups Leydig cell Control 2.2[+ or -]0.02 BD1/2 2.5[+ or -]0.15 (**) BD1/4 2.1[+ or -]0.03 The values (n=5) are presented as mean[+ or -]SD.
(B) Group II seminiferous tubules of goat with loss of cellular cohesion of the germinal epithelium, cytoplasmic vacuolization of spermatogonia and spermatocytes, sometimes with marginalized chromatin.
Op: primary oocyte, te: spermatic tissue, sp: spermatozoids, st: spermatocysts, sg: spermatogonia.
Spermatogonia and spermatocytes were especially more positively stained.
Photomicrographs of the cross-sections of seminiferous tubules represent the stages of spermatogenesis of seminiferous epithelium: spermatogonia type A (short arrows), primary spermatocytes at the pachytene stage (long arrows), spermatids at the zygotene stage (ellipse area) and spermatozoa (rectangular area).
In the testis, PLZF expression is restricted to As, Apr and Aal undifferentiated spermatogonia, including SSCs (25).
Type A spermatogonia at the basal lamina of seminiferous tubules, as well as primary spermatocytes in the leptotene and pachytene stages of prophase I, were also observed in the seminiferous epithelium.
Since rat spermatogenesis from spermatogonia to mature sperm takes about 9 weeks, in our study, all rats were sacrificed under anaesthesia of 3% chloral hydrate (1 ml/kg) 9 weeks after the last GnRHant injection.
The small populations of SSCs are the ancestors of numerous differentiated and specialized cells including spermatogonia, spermatocytes, spermatids, and mature sperms [2].
Immature and resting phase (Figure 8a) were covered the numerous spermatogonia and small seminiferous lobules was observed.
In a review, Parenti and Grier (2004) observed an evolutionary net on the teleosts testis morphology, through the organization of the seminiferous tubules and the distribution of spermatogonia throughout the germinal epithelium.