Reproductive development of the priapium fish Neosthetus lankesteri Regan, 1916 (Atheriniformes: Phallosthethidae) from Pranburi river estuary, Thailand using the histological approach

Abstract

Reproduction in the family Phallostethidae is an area that has long been of interest especially in gonadal structure and gametogenesis. However, no published data concerning as mentioned above in Neostethus lankesteri Regan, 1916 from Thailand is noted. This fish is important for rural livelihood in the estuarine fisheries of Pranburi River estuary, Thailand. The construction of the female reproductive system of N. lankesteri composed of the ovary and short oviduct. The mature ovarian morphology is a single organ, which is histologically considered to be an asynchronous development ovary. The differentiating oocytes were observed and classified into oogonia proliferation, primary growth phase, secondary growth phase, post-ovulatory phase and atretic follicle phase. Under the ovarian differentiation, our observation indicated that the ovarian parenchyma of N. lankesteri during 1.8 – 2.4 cm in standard length (SL) was accompanied by the secondary growth phases. Identification of the post-ovulatory phase was detected during our sampling periods, indicating to entire life in the Pranburi River estuary as well as true resident species. In the male reproductive system of N. lankesteri, the mature testicular parenchyma was organized morphologically as a single organ and histologically appeared to be a restricted spermatogonial lobular testis type. The differentiation of the spermatogenetic stage was composed of three phases including spermatogonial, spermatocyte and spermiogenetic phases. It was to identify possible trends that the size at first maturity of the female fish was estimated at 1.8 cm SL. Certainly, results from this study clearly showed on the reproductive pattern of N. lankesteri, which could be applied to further studies (the reproductive cycle, spawning season and histopathology).