Effects of Castration On the Activity of the Endocrine Dorsal Bodies of the Freshwater Pulmonate Snail Bulinus Truncatus, Intermediate Host of Schistosoma Haematobium

Abstract

In pulmonates Dorsal Bodies (DB) occur attached to the cerebral ganglia. These are endocrine organs producing a gonadotropic hormone (DBH). The DBH is confined in small (70-90 nm), membrane-limited granules in the cells. The contents of these granules is released by exocytosis. In the present study the hypothesis that DB activity is under hormonal feed-back control from the gonad was tested. For the experiments mature (3 month old) Bulinus truncatus were used. The DB of castrated and sham-operated snails sacrificed on post-operative days 13 and 65 were in- vestigated morphometrically. The results were statistically analysed. Castration has an important, stimulating effect on body growth. On day 65 the wet weight of the castrated animals was about twice that of the sham-operated snails. Also the volume of the DB and the mean number of cells per DB were larger in the castrated snails. However, most of the electron microscopical parameters measured (percentual volumes of Golgi apparatus, mitochondria and cytosomes, extensiveness of the endoplasmic reticulum, number of hormone granules and of phenomena indicating the release of the hormone) were not affected by castration, indicating that this operation has no effect on the synthesis and release of DBH. It is concluded from these results that DB activity is not under direct hormonal control from the gonad. This conclusion is sustained by the observation that regen- eration of the gonad after castration also has no effect on the ultrastructure of DB cells.