The Differentiation of the Zona Pellucida (Vitelline Envelope) in the Lizard Tarentola mauritanica

The organization of the zona pellucida in the lizard Tarentola mauritanica was studied at the transmission electron microscope. Evidence is provided in support of the hypothesis that follicle cells and the oocyte work together to synthesize and release components that give rise to the zona .
The components of the zona consist of fibrils and amorphous electron-dense material, which are first observed in young previtellogenic oocytes. These components seem to be released by coated vesicles that are formed by the Golgi complex in both the oocyte and the follicle cells. The material relased by the coated vesicles forms patches around the microvilli that project from the oocyte and the folds of follicle cells. During the following previtellogenic stages, the patches merge together to form a continuous coat around the oocyte. The coat persists until the end of vitellogenesis.