MALE-GROWN EGGS IN HYALOPHORA - DEFICIENT FOLLICLE CELL SECRETION AS WELL AS PROTEIN AND LIPID YOLK DEPOSITION

Ovaries transplanted to male Lepidoptera during late larva or pupal st ages produce smaller and fewer chorionated eggs than those remaining i n place or transplanted to other females. Small size is shown here in Hyalophora cecropia to result not only from a lack of vitellogenic hem olymph proteins but also from dysfunction of the follicular epithelium . Several aspects of egg formation can proceed normally in the male en vironment, including RNA deposition by the nurse cells, the conversion of lipophorin to a very high density form as the oocyte endocytoses i t, and the customary period of osmotic swelling between the end of yol k deposition and the beginning of chorion formation. But as would be e xpected, male-grown eggs lack vitellogenin and contain very little mic rovitellogenin. They also contain lower than normal amounts of lipopho rin, which is related to the male's poor ability to replace this prote in as the oocyte removes it from the hemolymph. A low phospholipid con tent can be attributed to the absence of vitellogenin and a low trigly ceride droplet content to the shortage of lipophorin. Two other defici encies, however, could not be directly explained by the low levels of vitellogenic hemolymph proteins: paravitellogenin and chorion, both se cretions of the follicle cells, are deposited in significantly reduced amounts. Males of this species, in addition to lacking sufficient vit ellogenic proteins and lipids in their hemolymph, are thus unable to f ully support the secretory activities of the follicle cells.