Regression of the epithelium in late previtellogenic follicles of Podarcis sicula: A case of apoptosis

Abstract

We investigated the reorganization of the follicular epithelium at the end of previtellogenesis in the lizard Podarcis sicula. In particular, we determined the mechanism of intermediate and pyriform cell regression and the fate of their different subcellular constituents. Morphological and biochemical analyses revealed the presence of hallmarks of apoptosis such as nuclear changes, chromatin condensation, protein scaffolds, RNA synthesis, and DNA fragmentation. It was therefore concluded that the remodelling of the follicular epithelium is associated with programmed cell death. Evidence was also obtained that during regression, the cytoplasmic constituents of intermediate and pyriform cells are transferred into the oocyte while the remnants of the nuclei are recycled by the small cells. The functional significance of these events is discussed. © 1996 Wiley-Liss, Inc.