Water Balance in Eggs

Abstract

The eggs of most arthropods contain a relatively large amount of yolk covered, at the time of laying, by a thin vitelline membrane (produced by the oocyte itself) and a more or less tough chorion, or shell, which is produced largely by the follicular cells of the mother. Unlike the cuticle of later stages, the chorion contains no chitin; it is more akin to “cuticulin”—a stabilized lipo-protein complex (Chap. 3.B.VI.). The chorion takes different forms in different insects (refs in Wigglesworth, 1972), but in all it has to provide mechanical support and protection, permit the exchange of respiratory gases, and prevent dehydration, flooding and loss of valuable solutes.