Ultrastructure of centrifuged bovine oocyte-cumulus complexes after pre-treatment with cytoskeletal relaxant

The objective of this study was the electron microscope examination of the localization of lipid droplets, mitochondria and other intracellular organe lles in bovine oocytes and cumulus cells after Cytochalasin B pre-treatment and ultra-centrifugation. Bovine (n = 180) oocyte cumulus complexes on a g erminal vesicle stage were treated with 5 mug/ml Cytochalasin B at 38.5 deg reesC for 10-15 min. They were then centrifuged at 15 800 g and fixed at 39 degreesC immediately after centrifugation in 3% glutaraldehyde with 0.5% f ormaldehyde for the microscopic examinations. The centrifugal pole of the o ocytes was filled with mitochondria. The centripetal part contained lipid g ranules and vesicles. Cytoplasm of low density was located in the equatoria l region. Hyaloplasm with spontaneously formed membrane and nonmembrane vac uoles was located in a supra-equatorial zone of the oocytes. In the cumulus cells the lipid vesicles formed one dark mass in the centripetal pole. The nuclei of these cells were deformed and vacuolization of the cytoplasm was noted.