Histoenzymological studies on embryonic and posthatching development of the ovary in the tropical oviparous lizard, <i>Calotes versicolor</i>

Abstract

The development of the ovary in the lizard Calotes versicolor has been studied histologically and histochemically from the day of oviposition (stage 27) to 2 months after hatching. The gonadal component appears as a genital ridge at stage 27. Sex differentiation of gonads occurs at stage 34, which indicates that the period of sexual bipotentiality is very brief. Oogenesis starts at stage 35, where preleptotene and leptotene oocytes appear for the first time in the ovary. The zygotene and pachytene oocytes appear during stage 36 and 38. Diplotene oocytes occur at stage 40. Folliculogenesis occurs 10 days after hatching. Follicles having a polymorphic membrana granulosa consisting of small, intermediate, and large round cells are found in 1-month-old hatchlings, and pyriform cells are observed in the granulosa of the ovary of 2-month-old hatchlings. The number of germ cells increases as development of the ovary proceeds. At oviposition, ∼236 and 244 germ cells were counted in right and left ovaries, respectively, and there was a manyfold increase in their number (to 4,234 and 4,294) at hatching. Mitotic germ cells are more abundant at stage 34, and no mitotic germ cells are seen after hatching. Histochemical localization of of Δ5-3β-HSDH and G-6-PDH activity is seen in the medulla of the ovary after sexual differentiation (stage 36), which indicates that the medulla of the ovary is the site of steroidogenesis. intensity of the enzyme activity remains more or less the same in the ovary up to 1 month after hatching and begins to increase thereafter. © 1994 Wiley-Liss, Inc.