α and β spectrin distribution during the differentiation of pyriform cells in follicles of lizard Podarcis sicula

• Published in: Molecular reproduction and development Vol. 67; no. 1; pp. 101 - 107
• Main Authors: Ricchiari, Loredana, Carmela, Vaccaro Maria, Marina, Prisco, Rosa, Carotenuto, Annamaria, Liguoro, Piero, Andreuccetti
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc., A Wiley Company 01-01-2004; Wiley-Liss
• Subjects: Animals; Biological and medical sciences; Cell Differentiation - physiology; Female; follicular epithelium; Fundamental and applied biological sciences. Psychology; Humans; In Situ Hybridization; Lizards - anatomy & histology; Lizards - physiology; Ovarian Follicle - cytology; Ovarian Follicle - metabolism; pyriform cells; Sexual differentiation and maturation. Puberty. Climacterium; spectrin; Spectrin - metabolism; squamates; Vertebrates: reproduction; Pyriform cell; Spectrin; Ovary; Vertebrata; Sauria; Spatial distribution; Female genital system; Reptilia; Differentiation; Ovarian follicle; In vitro; Podarcis sicula
• ISSN: 1040-452X; 1098-2795
• DOI: 10.1002/mrd.20008

Using α and β spectrin mammalian antibodies on Western blotting, we demonstrated that lizard ovarian follicles contain two isoforms of α spectrin, Mr 94 and 134 kDa, and a 230 kDa β spectrin, and that their pattern modifies in relation to pyriform cell differentiation. In fact, a positive immunoreaction is firstly evident within follicular epithelium of previtellogenic follicles when small cells differentiate into pyriform cells via intermediate cells. Later on, immunostain is present in pyriform cells and in the oocyte cortex that previously appears unstained. It is noteworthy that immunostain is also present on small cells located in contact with the oocyte membrane, but not on those located under the basal lamina and among pyriform cells, not engaged in pyriform cell differentiation. During the subsequent stages of previtellogenic phase, spectrin immunostain over the follicular epithelium and in the oocyte cortex does not change. By contrast, in vitellogenic follicles, when the follicular epithelium is constituted only by small cells, immunostain is evident at the level of the oocyte cortex and the cytoplasm of regressing pyriform cells. The present data strongly suggest that the α and β spectrin pattern put in evidence during the different phases of lizard oocyte growth is related to the differentiation of small into pyriform cells, where such protein may guarantee a relationship between surface glycoproteins (Andreuccetti et al., 2001: Anat Rec 263:1–9), and the cytoskeleton distribution (Maurizii et al., 2000: Raf Mol Reprod Dev 57:159–166). Furthermore, the distribution of spectrin mRNA, similar to that observed for the protein, demonstrates that spectrin, once synthesized within pyriform cells, is transferred through intercellular bridges in the oocyte cortex, thus confirming that pyriform cells are nurse that significantly are involved in the oocyte growth. Finally, the present data demonstrate that α spectrin of lizard ovarian follicles has Mr quite different from those so far reported and may constitute a new group of isoforms. This important result will be the focus of future experiments. Mol. Reprod. Dev. 67: 101–107, 2004. © 2004 Wiley‐Liss, Inc.