OBSERVATION ON GONADAL DEVELOPMENT IN TRIPLOID OSTREA CUCULLATA

During the peak period of its reproduction,external morphylogical features of gonad were under careful observation for diploid and triploid oyster,Ostrea cucullata, and with a comparison of mature oocytes and their nuclei in size. The results revealed that gonad in triploids showed poor development relative to diploids by appearances, the diameter of mature oocytes and their nuclei of triploids were 19.6% and 17.6% larger than those of diploids,and with 70.3% and 64.2% larger in volume.Histological sections presented that unlike diploids, gonadal development was retarded in triploids, of which the majority remained in stages of proliferation and spent,and only some of them developed to growth and mature stages and produce mature oocytes and sperm. Three hermaphrodites were observed in triploids sampled, which the sex ratio was female 7:male 1. In addition,retardation of gonadal development and hermaphroditic phenomenon of triploids are discussed in this paper.