An investigation of the presence of smooth endoplasmic reticulum and GERL during vitellogenesis in the ovary of Drosophila melanogaster.

The presence of a type of smooth endoplasmic reticulum often associated with the Golgi-endoplasmic reticulum-lysosome complex (GERL) is demonstrated in the cortical region of the nurse cells located in the vitellarium of the Drosophila melanogaster ovary. This proliferation of smooth endoplasmic reticulum/GERL-like structures appears to be restricted to the area of the nurse cells that are actually involved in endocytosis in the region of adjacent, non-vitelline membrane-forming follicle cells. Smooth surface vesicles are also found in conjunction with rough endoplasmic reticulum in a close-fitting arrangement enclosing follicle and nurse cell lipid vesicles suggesting an association of GERL with secretory body formation and lipid metabolism. Autophagic vacuoles (type 2) are observed near the 'trans' aspect of the Golgi while residual bodies are noted to be more distal to this region. The relationship of observed ultrastructural similarities during the oogenesis of an insect to previously established findings of GERL in a variety of mammalian cell types is discussed.