Role of pyriform cell during the growth of oocytes in the lizard Podarcis sicula

In order to clarify the role of follicle cells during growth of previtellogenic oocytes in lizards, an ultrastructural and autoradiographic investigation was carried out in Podarcis sicula. The evidence obtained clearly indicated that both intermediate and pyriform cells are actively involved in the synthesis of RNA that is then transferred to the oocyte, via intercellular bridges, apparently together with a variety of cytoplasmic organelles. At the end of the previtellogenic phase of growth, during the regression of the epithelium, the rate of synthesis of RNA in follicle cells is reduced, in particular in the nucleolus, but the flow of materials toward the oocyte continues. Thus, the intermediate and pyriform cells should be regarded as nurse cells even though they have characteristics rather different from those of the nurse cells described in other animals, such as insects. © 1995 Wiley-Liss, Inc.