Influence of pressmud on the development of the ovary, oogenesis and the neurosecretory cells of the earthworm Eudrilus eugeniae (Kinberg)

Abstract

The histology of brain neurosecretory cells and the development of the ovary and oocytes of preclitellate, early clitellate and late clitellate stages of Eudrilus  eugeniae reared in clay loam soil and pressmud have been studied. E. eugeniae reared in pressmud showed earlier differentiation of lobules in the ovary, and increased oocyte numbers with larger cellular and nuclear volumes than those reared in clay loam soil. This indicates the nutritional superiority of pressmud over clay loam soil in supporting gametogenesis. In the preclitellate stage, the brain neurosecretory cell types (A and B) are small and appear to be laden with secretory substances. The neurosecretory cells become vacuolated and show increased cellular and nuclear volumes and  nucleocytoplasmic indices during the reproductively active clitellate stages. Secretory activity of neurosecretory cells occurs earlier in worms reared in nutritively rich pressmud which has greater amounts of nitrogens, phosphorus and sugar, than in worms reared in clay loam soil.

Key words: Annelida, Oligochaeta, reproduction, nutrition, gametogenesis.