FSH non-antral follicles: theca cells. Theca cells (TC) forming one or two layers are seen by TEM in panels a, b. Lipid droplets (L) are visible in the theca cell cytoplasm (panel b). By SEM, the cells of the theca layer (TL) show a few surface expansions (panel c). Panel a, GC: granulosa cells; b: basement membrane. Bar is: 1 μm (panel a); 1.2 μm (panel b); 20 μm (panel c).