Figure 3. Effect of cholesterol depletion and repletion on polar body extrusion.

Zona-free mouse oocytes were incubated with 15 mM of MβCD for 30 min at 37°C to remove cellular cholesterol. Cholesterol repletion was carried out incubating MβCD-treated oocytes with MβCD/Chol complexes. After depletion/repletion treatments, oocytes were washed and inseminated. (A) Percentage of expulsed polar bodies (PB) after fertilization of cholesterol depleted oocytes. (B) Effect of cholesterol depletion and repletion on the extrusion of the second polar body visualized by DAPI staining. Inserts show a zoom of the regions indicated by asterisks. White arrowheads indicate PB and red arrowheads indicate meiosis arrest. Data in A represent the mean ± SEM of 3 independent experiments from a total of 55 control oocytes and 57 oocytes depleted at 15 mM MβCD. Asterisks (**) indicate significant differences with respect to control (P<0.01).