Gonocyte development in rats: proliferation, distribution and death revisited

Abstract

Spermatogonial stem cells are responsible for the constant production of spermatozoa. These cells differentiate from the gonocytes, but little is known about these cells and their differentiation into spermatogonia. This study analyzed rat gonocyte proliferation, death and distribution as well as their differentiation into spermatogonia. Rat testes were collected at 19 dpc and at 1, 3, 5, 8, 11 and 15 dpp and submitted to apoptosis investigation through morphological analysis and TUNEL, p53 and cleaved caspase 3 labeling. Ki67 and MVH labeling was used to check gonocyte proliferation and quantification, respectively. OCT4 and DBA labeling were used to check gonocyte differentiation. Seminiferous cord length and gonocyte numerical density were measured to check gonocyte distribution along the seminiferous cords. Although a reduction of gonocyte number per testicular section has been observed from 1 to 5 dpp, the total number of these cells did not change. Apoptotic gonocytes were not detected at these ages, suggesting that the reduction in gonocyte number per testicular section was due to their redistribution along the seminiferous cords, which showed continuous growth from 19 dpc to 5 dpp. The first proliferating germ cells were observed at 8 dpp, coinciding with OCT4 upregulation and with the emergence of the first spermatogonia. In conclusion, this study suggests that (a) gonocytes do not die in the first week after birth, but are rather redistributed along the seminiferous cords just before their differentiation into spermatogonia; (b) mitosis resumption and the emergence of the first spermatogonia are coincident with OCT4 upregulation.

Maternal obesity disturbs the postnatal development of gonocytes in the rat without impairment of testis structure at prepubertal age

“…Already high apoptosis levels observed at 14.5 dpp relate to the cells in the first wave of spermatogenesis. It should be mentioned that the immunocytochemistry for activated caspase 3 indicated a diffuse cytoplasmic labeling in rat gonocytes at 0.5 dpp, as observed by Zogbi et al (2012). The cytoplasm of all gonocytes at this age was labeled and a slight cytoplasmic staining could be seen until 7.5 dpp.…”

“…3D and E). The presence of activated caspase 3 in these cells can be explained by the fact that it is involved not only in the cell death system but also in the self-renewal and Gonocyte neonatal development following MO differentiation processes of germ cells (Fujita et al 2008, Zogbi et al 2012. According to Dejosez et al (2008), caspase 3 also recognizes critical pluripotency factors for embryonic stem cell function.…”

“…This parameter was estimated in order to examine whether the number of gonocytes in the same volume of seminiferous cord varied among the different experimental groups. These analyses were conducted based on the procedures of Roosen-Runge & Leik (1968) and Zogbi et al (2012).…”

The morphology of the testes of male albino rats at postnatal ontogenesis

“…22 The study of the index started from the 60th day of postnatal ontogenesis, as the migration of monoblasts and the first wave of spermatogenesis are over by this time. 16 This indicator, as the analysis showed, was of high level (3.32 ± 0.15), that is obviously related to the transition to the full-fledged spermatogenesis process, culminating in the formation of spermatozoa.…”

“…16 The formation of the first spermatogonia dates back to 3e6 day of 17 The analysis of the total content of spermatogenous cells in seminiferous convoluted tubules showed that spermatozoa, mature male sex cells, have a greater representativeness among all the spermatogenous cells in testes of experimental animals at the age of 2 months of postnatal development. Male stem cells, spermatogonia, take the second place in quantitative terms.…”