Gametogenesis in Schistosomatium douthitti (Cort) (Schistosomatidae: Trematoda)

Abstract

Spermatogenesis and oogenesis in S. douthitti follow, in general, the pattern reported for other trematodes. During spermatogenesis a primary spermatogonium gives rise by 3 mitotic divisions to 8 primary spermatocytes. Two maturation divisions result in a cluster of 32 spermatids. Mature spermatozoa are composed of thin, elongate bodies, each with 2 flagella. A zonation of cells occurs in testicular follicles. In each follicle, spermatogonial cells usually form a mass near the opening of the vas efferens, while clusters of spermatocytes and spermatids occupy the distal region. Oogenesis usually progresses through pachytene to a diffuse condition within the ovary. Primary oocytes leave the ovary in this diffuse condition. Within host tissues 2 polar bodies are produced in the normal manner and fertilization is completed. The diploid chromosome number in both sexes is 14.