Abstract
The epithelial sheath in the region surrounding vitellogenic oocytes is composed of a thin acellular, inner epithelial membrane, a median cellular network of muscular and tracheal cells, and an outer epithelial membrane. The inner epithelial membrane rests against the tunica propria, an acellular layer, which serves as a basement lamina for the follicle cells surrounding the oocyte. Thus, hemolymph molecules seeking access to the oocyte surface must pass through several barriers. The lumen between the inner epithelial membrane and tunica propria contains a group of plasmatocytes, each 10–15 μm in diameter, which apparently phagocytize sloughed off fragments of follicle cells and nurse cells.
