FINE-STRUCTURE OF THE EGGSHELL IN 2 HUMPBACKED FLIES, MEGASELIA-SCALARIS AND MEGASELIA-SPIRACULARIS (DIPTERA, PHORIDAE)

The present study deals with the fine structure of the shell in the ma in body of deposited eggs of 2 humpbacked flies Megaselia scalaris and M. spiracular is (Diptera: Phoridae). Eggs deposited within a period of 3 h were embedded for transmission electron microscopy. In ultrathi n sections, the overall architecture of the egg-shell was qualitativel y similar to that of Drosophila melanogaster. There were, however, a s eries of quantitative differences. A prominent vitelline membrane bord ered the plasma membrane. The chorion consisted of a thin inner layer, pillars, and a thin outer layer. There was a prominent external layer consisting of finely granular material. A 6-7 layered crystalline lay er, and an amorphous electron-dense layer separated the vitelline memb rane and the chorion. Hypochlorit treatment was used in order to deter mine the nature of this electron-dense layer. While all chorionic elem ents were removed, the layer in question was resistent to hypochlorit treatment, and therefore corresponds most probably to the wax layer fo und in Drosophila eggs. Copyright (C) 1996 Elsevier Science Ltd.