RESUMEN
This investigation was made on 30 adult female rats weighing approximately 150～200g. during estrus as judged from vaginal smear examination. Ovaries which investigated with electron microscope, were fixed in 3％ glutaraldehyde. Other ovaries were embeded in paraffin and examined under light microscope.Theca folliculi of large antral follicles were examined with electron microscope. Three kinds of theca cells were distinguished. They were secretory cell, fibroblast and smooth muscle cell. The secretory cell showed the characterastics of the steroidproducing cell, having smooth endoplasmic reticulum, mitochondria and lipid droplets. The fibroblast contained rough endoplasmic reticulum, free ribosomes and mitochondria in the cytoplasm. The smooth muscle cell was located in the outer layer of theca folliculi, and its structural features were typical according to the criteria of Somlyo and Somlyo: (1) pinocytotic vesicles of the cytoplasmic membranes; (2) myofilaments in the cytoplasm; (3) dense bodies intimately related to the myofilaments; and (4) location of mitochondria and endoplasmic reticulum at the nuclear poles.The ultrastructure of smooth muscle cell, its differentiation and other problems were discussed.
RESUMEN
The report of ultrastructure of dog ovarian follicle wall has not been seen yet. This investigation was made on 5 adult dogs in the estrus stage of the cycle and examined with electron microscope. There are granular cells, fibroblasts and secretory cells in the ovarian follicle wall, The typical smooth muscle cell is absent.