Development of spermatogonial stem cell niche and immunoexpression of vimentin filaments in the testes of prenatal and postnatal Indian buffalo (Bubalusbubalis)

Abstract

In this study, we established the components of the buffalo spermatogonial stem cell (SSC) niche in prenatal (38.5-280 days of gestation), neonatal, prepubertal, and adult testes histochemically and immunohistochemically. Immunohistochemically, the changes in vimentin expression were evaluated. During prenatal life, the niche of primordial germ cells was formed by the surrounding mesenchymal cells and fibroblasts. The basement membrane (BM) was not organized at this stage. At 7.6 cm crown-rump length, testicular cords with a thin BM were seen. At the late gestational period, testicular cords with well-organized BM were seen. At the neonatal stage, the testicular cords were lined with distinct BM, while during the prepubertal period, distinct BM with peritubular myoid cells (PMCs) were seen. In adult testes, the seminiferous tubules were surrounded by a thick BM surrounded by PMCs. PM cells were only single-layered as seen in H&E-stained paraffin sections, picrosirius red-stained, and Masson's trichrome-stained paraffin sections. Collagen fibers were seen to increase quantitatively to provide strength and cushioning to the developing niche of spermatogonial stem cells in the testes. The expression of vimentin increased to a certain extent until adult life, indicating its significant role as an intermediate filament during development.