Fig. 5. Oocyte wet mass (WM)/`initial control' (IC) wet mass (WM₀) ratio after a 60 h in vitro incubation. Follicle-enclosed oocytes were incubated in the presence of different steroids: 17,20ß-dihydroxy-4-pregnen-3-one (MIS40; 40 ng ml^–1); cortisol (5, 12 or 50 ng ml^–1); 11-deoxycorticosterone (DOC, 5, 12 or 50 ng ml^–1); cortisol (5, 12 or 50 ng ml^–1)+MIS40; DOC (5, 12 or 50 ng ml^–1)+MIS40. IC, initial control; ethanol vehicle was used as the negative control (NC). Values are means ± s.d. (N=5). Asterisks indicate significantly different from NC. Triangles indicate significantly different from MIS40 value (P<0.05). The percentage of germinal vesicle breakdown (GVBD) after 60-h incubation is shown below for each group.