Spermatogenic Ultrastructure of the Grunting Toadfish Allenbatrachus grunniens (Batrachoididae)

In the present study, we describe the spermatogenesis of Allenbatrachus grunniens, a benthic toadfish from Estuarine Pranburi River, Thailand, at the ultrastructural level. According to the nuclear and cytoplasmic characteristics, A. grunniens spermatogenic cells are classified into five stages. The spermatogonium contains the prominent nucleus and locates in the periphery of the seminiferous lobule. The spermatogonium develops into the primary spermatocyte and then into secondary spermatocyte, which was characterized by the dramatical increase in heterochromatin. The subsequent spermatids exhibit the centriole formation, chromatin condensation, mitochondrial redistribution, and reduced cytoplasm. After the final morphological differentiation, the spermatozoon shows an oval head with a high degree of chromatin condensation, a small midpiece consisted of prominent basal bodies surrounded by eleven mitochondria, and the biflagellate tail. Our observation demonstrates the ultrastructure of Batrachoididae spermatozoa, which can help to understand their reproductive biology.