Fig. 2. Histological analysis of wild-type and Tex12^–/– testes and ovaries. (A) Spermatogenesis is halted at epithelial stage IV in the Tex12^–/– testes leading to a total absence of round and elongated spermatids. Stages of the seminiferous epithelium are shown as roman numerals. Different testicular cell types depicted are: Int, intermediate spermatogonia; Ls, leptotene spermatocytes; Zs, zygotene spermatocytes; Ps, pachytene spermatocytes; Ps^*, apoptotic spermatocytes; Ds, diplotene spermatocytes; M, meiotic cell division; Rs, round spermatids; Es, elongated spermatids; Ser, Sertoli cells. Oogenesis proceeds until the dictyate arrest stage, even though 30% of the oocytes are lost during early embryonic development. After birth, the Tex12^–/– oocytes degenerate rapidly and virtually no oocytes can be found in ovaries more than 1 week after birth. Oocytes are labeled with anti-GCNA (brown). Bars: 20 µm (testes) and 5 µm (ovaries). (B) Average number of oocytes (± s.e.m.) per ovary in wild-type and Tex12^–/– ovaries at embryonic stage E16.5 and day 1 after birth (n=3).