Gametogenic processes in the pearl oyster, Pteria penguin (Röding, 1798) (Bivalvia, Mollusca)

Abstract

The aim of the study is to reveal the gametogenic cycle in the pearl oyster, Pteria penguin. The specimens were collected from Si-chang Island (Thailand) from January 2000 to January 2001. Gametogenesis was observed in histological preparations of gonads from 142 adults sampled monthly. Spermatogenesis was classified into 10 stages: spermatogonia, 5 stages of primary spermatocyte, secondary spermatocyte, 2 stages of spermatid, and spermatozoa. Oogenesis was comprised of 6 stages: oogonia and 5 stages of oocyte. Three stages of gonad development were identified in the male: developing, mature, and partial spawning. In the female, there were 4 stages of gonad development: developing, mature, partial spawning, and spent. The spawning cycle of the male was observed throughout the year with a peak of partial spawning in March to June (60%) and in December to January (40%). Females spawned in June and July (50%). The water temperature and the salinity were not correlated to the reproductive cycle of P. penguin. The results of this study can be applied to the induction of spawning and the production of seed in the aquaculture system of this pearl oyster species.