We had to elucidate the normal physiology of the female cells of H. aspersa
in order to interpret their evolution under experimental conditions. This study
points out some interesting aspects which merit investigation, such as the nature
and functional significance of nucleolus-like bodies and of weakly contrasted
fibrillar nuclear material, and the origin of the yolk. Using labelled carbohydrate
and amino acid precursors, we are currently trying to determine the ways in
which the Golgi apparatus, and probably the RER, participates in the
development of the endogenous yolk. The use of horseradish peroxidase
demonstrates some endocytotic phenomena, but the problem of exogenous
protein incorporation from the hemolymph into the oocytes is not clear ; the
importance of this process in H. aspersa oogenesis remains to be determined as
well as the putative participation of the follicle cells in the synthesis of oocyte
reserves.