Some Observations on the Reproductive Duct of the Japanese Sea Bass, Lateolabrax japonicus (Cuvier and Valenciennes).

Abstract

The microscopical structure of the reproductive ducts of L.japonicus has been studied.Both spermiduct and oviduct of the fish are single, short organs, and are characterized by the folded condition of tunica propria lined with a single epithelial cell layer mainly consisting of cuboidal or squamous cells.No cyclic changes of the epithelium and the tunica propria have been observed except that the vessels in the tunica propria became filled with blood at the spawning time and that the partial stratification of epithelial cell layer was found in the spermiduct of mature male collected in early January.Judging from the histological features, the duct seems to serve mainly as a pathway of gametes from the gonad to the extremity.It was also believed that the spermiduct may play a certain role in a degenerating process of the remaining spermatozoa in the duct.The oviduct is closed in the immature females as well as in the adult females in the months intervened between the spawning seasons, as observed in some other teleosts.The orifice is produced between the anus and the urinary orifice just prior to ovulation.