Figure 1: Immunolocalization of 5-methyl cytosine on adult human testicular section and peri-menopausal ovary surface epithelium smear (using standard protocol published earlier, [55]). Note dense staining in the spermatogonial stem cells (SSCs, arrow, (a)) while the spermatocytes showed minimal staining. In few tubules spermatids showed positive staining. Similarly the ovarian germ stem cells (OGSCs) stain positive ((b) and (c)) Negative control (d). The results indicate that Adark SSCs in testis and OGSCs in ovaries, derived by asymmetric cell division of VSELs undergo nuclear reprogramming associated with extensive methylation—suggesting that similar basic stem cell biology exists in both the sexes. Scale bar = 20 μm.