Histological Study On Follicular Development Of Sika Deer (Cervus Nippon Hortulorum) Ovary

Seven female Skia deer(Cervus Nippon Hortulorum)(4-5years) that were in oestrum and anoestrum were used to explore the changes of histological structure during follicular development with light and electron microscopes. The results were as follows:1. The method of making serial sections was used to study the histological structure of follicles, and to measure the size of all kinds of follicles and the oocytes embraced by them. Primordial follicle consisted of an oocyte and a single layer of flat follicle cells, and the average diameter of primordial follicle and the oocyte were respectively 37.09μm and 27.72μm. One to four layers of follicle cells surrounded the primary follicle around which follicular theca gradually came into being. The average diameter of primary follicle and the oocyte were 86.18μm and 43.12μm. Oocyte of secondary follicle was surrounded by over four layers of follicle cells. There were some lacunae and spaces between follicle cells and follicular theca was clearer. The average diameter of secondary follicle and the oocyte were 284.59μm and 85.13μm. In vesicular follicle there was a large follicular antrum. The oocyte located in one side of the follicular antrum and with more and more granulose cells around it came into being cumulus oophorus, the structure of which is typical radiated corona. The average diameter of teriary follicle and the oocyte were 993.61μm and 103.05μm. Granulose cells of mature follicle was incompact.2. The results of studying the histological character of follicular atresia showed that at the beginning of primordial follicle's atresia, the oocyte presented regressive changes and shrinking, the nucleus of follicular cells became pycnotic. During primary and secondary follicle's atresia, the oocyte began to deform and shrink, its nucleus became pyenotic, zona pellucida deformed, the basal lamina disappeared, the follicle's shape became irregular, and its nucleus got to be very compact. The teriary follicle's atresia included early, advanced and late these three stages.3. The changes of follicular cells' ultrastructure were studied by transmission electron microscope (TEM). The shape of primordial follicile cells in which there was few organdies was spindly or long and flat. Much heterochromatin along the nucleus could be seen clearly and the nucleus had a large proportion in these follicle cells. In the cubical or unilaminar follicular cells, the nucleus became round or elliptic and located on the bottom, the number of organelles increased, and the structure of organelles became clearer. In primary and secondaryfollicle cells, mitochondria was round or elliptic, which was often surrounded by roughendoplasmic reticulum, the free ribosome could be seen a lot, and the projections of follicleextended through zona pellucida. In the cytoplasm of the teriary follicle, there were manyGolgi complex, endoplasmic reticulum and ribosome. Microfilaments widely lied in thecytoplasm of granulose cells.4. During different developing stages of the follicles the oocytes' ultrastructure had many changes. At primordial follicle stage, the oocyte was round and its plasma membrane smoothly sticked to the follicle cell's, most organelles located near the nucleus, Golgi complex was not typical, and most mitochondria with few Cristae were round. At primary and secondary follicle stage, follicles locally formed zona pellucida when they consisted of three to four layers of follicle cells, irregular microvili on the oocyte were present in the zona pellucida, organelles were well distributed in the cytoplasm, and the number of mitochondria, cortical granules and smooth endoplasmic rericulum had all increased. At teriary follicle with 0.5-1.5mm diameter stage, zona pellucida became thick, the number of rough endoplasmic rericulum decreased obviously, and all kinds of organelles and Golgi complex increased in the cortex. At with 1.5-3mm diameter stage, the thickness of zona pellucida kept on increasing, the microvili on oocyte became short and curving and withdrew from the zona pellucida, and a lot of cortical granules began to laid beneath the plasma membrane of oocyte. In the cortex most organelles distributed and there were many Golgi complex.