The differentiation and proliferation of follicle cells during oocyte growth in Lacerta sicula.

The follicular epithelium of the lizard oocytes undergoes structural and morphological modifications throughout oocyte growth. During this process the number of follicle cells increases and the epithelium acquires a multilayered and polymorphic organization which is characterized by the appearance of large follicle cells (intermediate and pyriform cells). The number of large cells also increases during oocyte growth and this increase parallels that of small cells. However, only the small cells become labelled one hour after [3H-]thymidine administration. Large cells have been found labelled after a longer period of time, i.e. 4--5 months after isotope injection. All these results together indicate that large follicle cells arise from the differentiation of small cells.