Fig. 1. Representative morphology in the ovary (A—D) and testis (E—H) of P. depressus at different stages. Paraffin-embedded sections were stained with Hematoxylin and Eosin. At stage 1 (A,E), the gonadal lumina are filled with nutritive phagocytes. At stage 2 (B,F), many developing oocytes or clusters of spermatogonia are present at the periphery. At stage 3 (C,G), nutritive phagocytes are replaced with ripe ova or spermatozoa in the center of the lumina. At stage 4 (D,H; fully mature gonad), the lumina are filled with ripe ova or spermatozoa. NP, nutritive phagocyte; OC, oocyte; OV, ripe ovum; SG, spermatogonium; SC, spermatocyte; SZ, spermatozoon. Scale bar, 100 µm.