Changes in the ovary cells structure in the earthworm Dendrobaena veneta (Rosa) in neurosecretion deficiency and after exposure to cadmium

Abstract

In the earthworm Dendrobaena veneta, anterior parts of body were removed at segment 6 and 20 days after decerebration the ovary ultrastructure of these specimens was examined. Numerous changes in oocytes, including shrunk ooplasm, changes in shape, damage of microvilli and oocyte sheath, as well as occurrence ER whorls made it impossible for oocytes to complete oogenesis and caused their degeneration. Similarly, dramatic degenerative changes occurred in Golgi complexes and ER in trophocytes, which might result in disturbances of vitellogenesis. Decerebration deprived the earthworm of neurosecretion (gonadotropins), which resulted in oogenesis distortion. The obtained results were discussed with the results of previous experiment. Then the ovary ultrastructure was described in the individuals maintained in Cd contaminated soil for 20 days. The results in both experiments proved very similar. It may be assumed that cadmium might affect oogenesis in D. veneta in indirect way by suppressing neurosecretion synthesis and its release.