Ultrastructural rearrangements of the vitelline envelope during egg development in eyprepocnemis plorans (Charp.) (orthoptera, acrididae)

The vitelline envelope of Eyprepocnemis plorans eggs undergoes rearrangement after ovulation. This modification involves the gradual condensation of the original structure, which separates from the oolemma, and the elaboration of an underlying granular layer. Both these layers reach their definitive arrangement at an advanced stage of embryogenesis, probably fulfilling a similar functional requirement for egg water-exchange. A study of parthenogenetic eggs was also undertaken to evaluate the role played by the male gamete in these modifications. The results show that while vitelline envelope rearrangements are independent of fertilization, this seems to be indispensable for the genesis of the granular layer.