Sex steroid hormone fluctuations and morphological changes of the reproductive system of the female of Octopus vulgaris throughout the annual cycle

Sex steroids (17 beta -estradiol and progesterone) and morphological variat ions of the reproductive system of the female of Octopus vulgaris from the Bay of Naples were followed over a period of 2 years. The increase in the o vary weight was independent of body weight as demonstrated by the gonado-so matic index (GST). Both 17 beta -estradiol and progesterone have been detec ted in the ovary of O. vulgaris, and their concentrations changed in correl ation with the ovarian development. No 17 beta -estradiol or progesterone w as found in the hemolymph. 3 beta -Hydroxysteroid dehydrogenase activity ha s been detected in the ovary, indicating that in the female of O. vulgaris the reproductive system is a source of sex steroid hormones. According to t he morphological changes of the ovary, the ovarian cycle can be divided int o the following phases: previtellogenesis; early vitellogenesis, full vitel logenesis and late vitellogenesis. The morphological changes of the oviduct s and oviducal glands throughout the reproductive cycle were in accordance with their role in the transport and secretion of gelatinous coat covering the eggs, as well as in sperm storage and sperm reactivation during fertili zation. J. Exp. Zool. 289:33-47, 2001. (C) Zool. Wiley-Liss, Inc.