Some Degenerative Phenomena in Drosophila Ovaries

Abstract

ABSTRACT A description is given of degenerative phenomena in the Drosophila ovary. Three types of degeneration are dealt with: (1) degeneration of the follicle cells; (2) degeneration occurring in the unfertilized egg, a major feature of which is the segregation of the different constituents of the egg into comparatively large masses; and (3) degenerative phenomena in the nurse cells and oocytes of abnormal eggs produced in ovaries homozygous for deep-orange. In all these instances it is noteworthy that a considerable degree of structural organization (formation of double membranes, or sets of parallel or concentric membranes, &c.) occurs in cytoplasm which is clearly degenerating. It is suggested that such organization does not always represent the formation of functioning organelles, but may be a mere consequence of the inherent physicochemical properties of the materials involved. In degenerating deep-orange ovaries masses of fragmented porous membranes are found. These seem to be derived from the nuclear membranes of the nurse cells, which appear to persist even when the rest of the cell is rather completely destroyed. Fragments of nuclear envelopes tend to lie close together and parallel to one another, and it is suggested that this indicates that there is some force of attraction between them, which may be comparable to the forces involved in the formation of stacks of annulate lamellae, or of concentric or parallel double-membrane structures in ergastoplasm, and in chromosome pairing in healthy functional cells.