Localization of alpha-tubulin in the rat cumulus oophorus before and during preovulatory expansion

Distribution of alpha-tubulin was investigated in the cumulus oophorus complexes (COCs) of the rat using anti-alpha-tubulin monoclonal antibody and fluorescence microscopy. Localization of alpha-tubulin was assessed in the compact and fully expanded COCs isolated directly from the preovulatory follicles and in the cryosections containing these structures. In the cryosections containing COCs, the submembranous distribution of alpha-tubulin marked the characteristic cell shapes and showed the lack of cell projections. In the freshly isolated COCs three-dimensional cellular arrangement was visible showing that the dispersed cells formed almost no projections and were not interconnected. The use of a higher magnification revealed a dense microtubular network radiating from centrosomes and extending to the plasma membrane. This network showed discontinuous distribution of submembranous alpha-tubulin in some of these cells. The latter change could be attributed to the increased progesterone production.