Comparative developmental physiology and molecular cytology of the polytrophic ovarian follicles of the blowfly Sarcophaga bullata and the fruitfly Drosophila melanogaster.

1. The ovarian follicles of Sarcophaga and Drosophila consist of one oocyte and 15 nurse cells, the whole being surrounded by follicle cells. Although oocyte and nurse cells are genetically identical sibling cells, and although they are interconnected by cytoplasmic bridges, their physiology is very different.

Intra- and Extracellular Electrical Fields of Vitellogenic Polytrophic Insect Follicles.

Dye-coupling of lucifer yellow between follicle cells and germ cells of the vitellogenic polytrophic follicles of Sarcophaga bullata, Drosophila melanogaster, and Manduca sexta does not always occur. The electrical field around the follicles of Sarcophaga bullata can be modified by altering the ionic composition of the Ringer solution. We propose general model that suggests possible pathways for both intracellular and extracellular current loops.

Polyploidization and localisation of poly(A)+ RNA in the different cell types of the vitellogenic meroistic ovary of the fleshfly, Sarcophaga bullata.

The degree of polyploidization, the level of transcriptional activity and the volume of the different cell types present in the meroistic ovary of Sarcophaga bullata were measured during different vitellogenic stages. The nurse cells and the germinal vesicle exhibited very pronounced differences with regard to DNA content and mRNA synthesis, even though they are genetically identical. During the 4C stage (late vitellogenesis), we observed different degrees of polyploidy in follicle cells adjacent to the oocyte and those surrounding the nurse cells.