The Seasonal Effect On The Follicular Development And Atresia Of Yimeng Black Goat

Oestrus cycle arises after sexual maturation in female mammal. It is regulated by the internal factors such as endocrine and nervous system and affected by outer enviroment such as season.To make it clear that how the season affect the development and atresia of follicle in Yimeng black goat. we carried out three experiments.Experment one:The histological structure of the ovary of Yimeng black goat was studied. The results as follows:The primordial and primary follicle spread in groups,few follicles had two oocytes.There were no significant relation between the diameter of oocyte and thickness of ZP. In the preantral follicle,the thickness of base membrane did not change with follicular size.In primordial follicle. only desmosome could be seen between oocyte and granulose cell.The atresia rate was lower in preantral follicle: follicular atresia rate of Primordial follicles ,primory follicles and secondary follicles were 8.5%.14.3%.16.8% respectively . The degeneration of oocyte was main character in primordial follicular atresia . oocyte and granulose cell degenerated at the same time in secondary follicle.Experiment two:Research was carried out on the development of the follicle with the method of making serial sections.The results show:the number of the visible follicle on the surface of ovary was the fewest in summer .It has significant difference between summer and spring. The number of visible follicles was lower at luteal phase than follicular phase ,having the same change with follicular phase.The effect of season on the number of primordial , primary follicle and secondary follicle was not notable, it was no significant difference among seasons.Small vesical follicle followed.The season affectesthe atresia of the large vesical follicle significantly. two ovaries of Yimeng black goat had similar function.Experiment three: As the results show: apoptosis exsisted in follicle.The major type apoptosis cell was granusola cell in vesical follicle.The apoptosis of granular cell and follicular inner membrane cell appears late.Few apoptosis nucleus of oocyte could be seen in preantral follicle, but there was no apoptosis nucleus in intestinal cell .A few surficial epithelium have apoptosis.TUNEL and HE are two effective means on detecting apoptotic granulosa cells.