Co-localization of androgenic enzymes, P450c17 and 3βHSD, and accessory protein, cytochrome b5, within the theca interna cell layer (arrows) of (A–C) antral [(D–F) box inset], (G–I) advanced secondary, (J–L) early atretic, (M) late atretic follicles, and (N, O) secondary interstitial cells in the ovarian stroma. Bars represent 30 μm for D–F, N, O; 40 μm for G–I; 100 μm for A–C, M; 200 μm for J–L. TC, theca interna cells; GC, granulosa cells; Aa, advanced atretic follicle; An, antrum; Prd, primordial follicles; Prm, primary follicles