Occurrence of intercellular bridges between follicle epithelial cells in the ovary of Apis mellifica queens.

Hitherto unknown intercellular bridges or fusomes between the follicle epithelial cells investing the oocytes of Apis mellifica queens have been observed both with light and electron microscopy. Usually each follicle cell has 2-3 intercellular bridges. In surfacial paraffin sections, the intercellular bridges can be seen to connect a series of follicle cells which may be branching. The intercellular bridges lie close to the egg cortex and this position is relatively constant. The width of the fusomal ring canal varies in different developmental stages. In stages 3 and 4 of oogenesis, which are the main vitellogenic stages, the intercellular bridges measure 0-5 micron, while in stages 1 and 2 they have a diameter ranging from 1-5 to 3-5 micron. In these stages the intercellular bridges are provided with numerous transverse microfilaments which disappear later. The fusomal lips are thickened and consist of electron-dense material and an additional layer of less electron-dense material both inside and outside. Ribosomes flow across the bridge. The intercellular bridges may serve to synchronize the differentiation and functional activity of the follicle epithelium during the course of oogenesis.