Insect egg cortex isolated by microsurgery: Specific protein pattern and uridine incorporation.

Egg cortex material (ECM) containing the oolemma and adherent periplasm has been isolated from an insect egg by means of micromanipulation. Analysis of proteins by SDS-PAAG-electrophoresis demonstrated striking differences between the protein banding patterns of ECM and of whole eggs. ECM and whole eggs also differ clearly with respect to3H-uridine uptake; the ECM contains RNA labeled during the previtellogenetic period of oogenesis (probably in the germarium) but, in contrast to the central parts of the oocyte, is largely void of label taken up during the last stages of oogenesis.