Oogenesis in Acerentomon gallicum Jonescu (Protura). An ultrastructural analysis of the early previtellogenic stages.

At the onset of previtellogenesis, the oocytes of Acerentomon gallicum begin to grow and increase their content of organelles. The nuage material in the oocytes at first increases in amount, then declines gradually to disappear completely from oocytes that have attained 50 micrometer in diameter. During the growth period, new dictyosome, mitochondria and ribosome appear. Numerous vesicles become detached from the cell membrane and subsequently fuse into cisternae, thus forming extensive complexes of the rough endoplasmic reticulum. In oocytes with diameters between 50 and 100 micrometer the endoplasmic reticulum. In oocytes with diameters between 50 and 100 micrometer the Golgi complexes show a considerable increase in activity, and many lamellar bodies arise from mitochondria that have undergone specific transformation.