Photomicrographs of testes of Astyanax aff. bimaculatus in different phases of gonadal maturation. (7) Immature. Only primary spermatogonia (Sg1) without lumen. (8–9) Developing. Various types of spermatocytes evident along lobules (Sg2, Sc1, Sc2, St, Sz) and germinal epithelium (GE) continuous throughout. (10) Spawning Capable. Predominance of Sz in lumen seminiferous tubules. (11) Regressing. Presence of cysts (Cy), residual spermatozoa (Sz) and germinal epithelium (GE) in regeneration. (11) Regenerating. Proliferation of spermatogonia (Sg1, Sg2) and GE continuous throughout. Staining haematoxylin and eosin (HE). Scale bar: 20 μm.