Abstract:
Clams, Meretrix meretrix (Linnaeus, 1758) (Bivalvia : Veneridae) were collected from Bangsaen Beach, Chonburi, from January to December 1996, and examined using histological analysis through a paraffin technique in conjunction with hematoxylin and eosin staining for the study of gametogenesis, gonadal development and the spawning cycleClams in this study had an average maximum shell length of 52.19+-9.09 mm (n=120). Sex ratios between males and females were 0.86 : 1 (45 males and 52 females). Oogenesis was divided into six stages : oogonium, and oocytes stage 1-5, primary young oocyte, secondary young oocyte, previtellogenic oocyte, vitellogenic oocyte and mature oocyte, whereas spermatogenesis was divided into four stages, spermatogonium, spermatocyte, spermtid and spermatozoa. The gonadal development cycle was classified into six stages : prefollicular development, initial development, developing, mature, partially spawned and spent. There were two peaks of spawning, in May (90%) and in September (70%).