Studies On Histology And Immunocytochemistry Of Ovaries Of The Rana Quadranus And The Batrachuperus Tibetanus

The development of amphibian oocyte is extensively regulated by various factors. Sex steroids and their receptors, proto-oncogenes play key roles in the regulations. Studies on the regulations of steroids, receptors and proto-oncogenes during the follicle development, and studies on these multual relations, have great significance in the study on the mechanism of the oocyte development. Firstly, using histological method,the thesis studied the peroid of follicle development of the Rana quadranus and the Batrachuperus tibetanus. Secondly, the studies of regulations of estradiol, progesterone, testosterone, and their receptors, c-myc, c-fos during follicle development of this two amphibians were carried out by using immunocytochemical method. The results are as follows.1. The obvious individual difference exists in the ovary of the Rana quadranus. Each female only ovulates once every year and the ovulation lasts a very short period of time. However, for the community that lives in Qinling mountain area, the spawning period start in Apr, and end in Jun.2. There is little difference among the individual of the Batrachuperus tibetanus. Each female only ovulates once every year, while the whole community's spawning period lasts from Mar to Apr.3. One of significance of the follicle atresia of the Rana quadranus and the Batrachuperus tibetanus is that it makes the amount of oocyte under control and it guarantees sufficient oocytes maturation under the condition of limited nutrition. The corpora atrestics which are mainly formed at III and IV stages of follicle development are probably have the ability to secrete steroids.4. For the Rana quadranus, the follicle cells are the main sites for estradiol(E2) and progesterone(P), whereas the thecal cells are the primary source for testosterone(T). They cooperate with each other and accomplish the secretion. From the point of morphology and immunocytochemistry, it is proved that it is reasonable to analysis the follicular steroidogenesis of the Rana quadranus by using the two-cell type model.5. For the Batrachuperus tibetanus, the follicle cells are the main sites for e2, P and T, but the thecal cells are not shown to product steroid. So we propose that the steroidogenic cells in the ovary do not differentiate in their funtions, which shows primitive characteristic in reproduction of urodeles.6. E2 plays a key role in the synthesis and accumulation of yolk protein of the Rana quadranus and the Batrachuperus tibetanus. P and T regulate oocyte maturation of the Rana quadranus, but only P in the regulation of the Batrachuperus tibetanus. That shows there are some difference in the steroid regulation between the anuras and the urodeles. Among three of the steroid, one can convert to the other, and some enzyme activity is concerned with the conversion.7. For the Rana quadranus and the Batrachuperus tibetanus, the steroid receptors play key roles in the synthesis and secretion of the steroids and during the development of the follicle cell. The receptors can function in two ways. One is as signal transducers outside of the nucleus, named nongenomic action. The other is as transcription activators in the nucleus, named genomic action. The two ways may coexist, cooperate and coregulate in the development and maturation of oocyte.8. C-myc maybe plays a role at the early stage of oocyte development of the Rana quadranus and the Batrachuperus tibetanus, and c-fos at the medium and later stages. Two of the protogenes have some correlation with the three steroids during the oocyte development.9. The corpora atrestic of the Rana quadranus and the Batrachuperus tibetanus are shown to produce E2 to stimulate the synthesis of yolk protein. Estrogen receptor and progestogen receptor in the corpora atrestic regulate the endocrine function of ovary to maintain proper estradiol secretion.