Fig. 3

Histological analysis of zebrafish gonads from different experimental groups. (A-C) Testis (tes) of a diploid (2n control) control zebrafish showing full spermatogenesis with lumina (lu) filled with spermatozoa (spz). (D-F). Testis of a triploid (3n control) zebrafish showing preserved testicular organization but depleted spermatozoa (spz). Pycnotic nuclei (pyc) are observed in some spermatocysts, indicating degeneration of spermatogenic cells. (G-I). Ovotestis of a diploid zebrafish treated with 17α-ethinylestradiol (2n + EE2), resulting from partial feminization. Note the presence of a rudimentary testis (rdt) and an ovary (ova). Panel H shows a magnification of testicular tissue with multiple spermatogenic stages while panel I shows a magnification of the ovary containing both previtellogenic (pvo) and vitellogenic oocytes (vto), (J-L). Underdeveloped ovaries of a diploid zebrafish treated with EE2 (2n + EE2), containing only previtellogenic oocytes. (M-O). Testis of an EE2-treated triploid (3n + EE2) zebrafish. Note the reduced number of spermatocysts (cys), enlarged lumina (lu), abundant groups of spermatogonia A and B (spgA and spgB, respectively), the presence of pycnotic nuclei (pyc), and the absence of spermatozoa (spz). Abbreviations: testis (tes), rudimentary testis (rdt), spermatocyst (spc), spermatogonia A (spgA), spermatogonia B (spgB), primary spermatocyte (spc 1), secondary spermatocyte (spc 2), spermatid (spt), spermatozoa (spz), pycnotic nuclei (pyc), lumen (lu), ovary (ova), rudimentary ovary (rdo), previtellogenic oocyte (pvo), oil droplet oocyte (odo), vitellogenic oocyte (vto). Staining: hematoxylin-eosin.