General appearance of in vitro grown follicles. FCS follicles (panels a, b); FSH antral follicles (panels c, d); FSH non-antral follicles (panels e, f). The general appearance of cultured follicles is shown by LM (panels a, c, e) and SEM (panels b, d, f). Panels a-f, O: oocyte; GC: granulosa cells; TC: theca cells. Panels a, c, e, ZP: zona pellucida; b: basement membrane. Panel c, asterisks: fluid-filled spaces. Bar is: 30 μm (panel a); 100 μm (panels b, d); 50 μm (panels c, f); 45 μm (panel e).