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H. Okamura, A. Takenaka, Y. Yajima and T. Nishimura

Summary. The apical wall was studied ultrastructurally in 16 human follicles at various stages of development. In the theca externa and tunica albuginea at the apex of growing follicles, fibroblasts with little cytoplasm and abundant collagen fibres were observed. In the mature follicles, the fibroblastic cytoplasm was well developed, rich in lysosome-like granules and contained peripheral multivesicular structures. Intercellular collagen fibres were sparse. It is suggested that the collagen fibres are digested by the content of lysosomal granules and multivesicular structures, thus aiding follicular rupture.

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M. Koshida, A. Takenaka, H. Okumura and T. Mori

Summary. Immature Wistar rats were induced to ovulate by treatment with PMSG and hCG. Control animals ovulated 43·5 ± 0·36 ova/rat. Intraperitoneal injection of rotenone doses of 0·125, 0·25 and 0·50 mg/kg reduced the ovulation rate to 24·0 ± 3·08, 8·0 ± 0·88 and 1·5 ± 0·44 ova/rat, respectively. The rotenone significantly reduced ovarian cytochrome oxidase activity and progesterone production, but not production of oestradiol or testosterone. Thyroxine treatment at a dose of 5 mg/kg s.c. reversed the rotenone inhibition of ovulation. The results suggest that an increase in mitochondrial respiration is an essential feature of the ovulation process in mammals.