The Studies On Histological Characteristics Of Follicular Systems And Corpus Luteum In Yaks During The Estrous Cycle

Forty-eight female yaks(3-7 years) with known the two continuous estrous cycles were used to determine the histological structure of follicular systems and corpus luteum of their ovaries with light and electron microscopes. The results were as follows:1. To determine the numbers and sizes of all kinds of follicles in the estrous cycle and observe their histological structures. The average total numbers of primordial follicles and growing follicles per ovary pair were not different significantly (P>0.05) in the diestrous, estrous, metestrous and anestrous . The numbers of antral follicles in the diestrous was similanT > 0.05) with the other three stages. The number of antral follicles in the anestrous was different significantly (P<0.05) with that in estrous and metestrous stages. The average total numbers of atretic growing follicles per ovary pair were similar (P > 0.05) in the estrous cycle. The numbers of atretic antral follicles in the estrous stage were different significantly (P<0.05), the numbers in metestrous stage different significandy(P<0.05) with that in the diestrous and anestrous stages.2. To measure the sizes of all kinds follicles and their oocytes, and the sizes of lutein cells. The diameters of primodial, primary and secondary follicles were 30.8?6.4 y. m, 53.6?44 u m, and 152?08 n m respectively; the sizes of their oocytes were 17.6?4.4,18.8?1.7 u m and 78.2?6.5 u m respectively; and the diameters of the nuclei of their oocytes were 8.7?3.9n m,10.1?7.5u m^nd 17.7 ?9.5 u m. The average diemeters of the GLC and TLC of mature corpus luteum were 36.6 u m and 14.4 u m respectively, their nuclei were 15.2 u m and 10.9 V- m, respectively.3. To investigate the histological structure and ultrastructure of corpus luteum, and study the connective tissue changes in the forming and regressing of them. The corpusluteum were divided into four stages depending on the estrous cycle. The corpus luteum contained of two kinds of lutein cells: granulose luteal cells (GLC) and theca luteal cells (TLC). Tlie characteristic changes of GLC and the connective tissue distributed were more distinct in the forming and regressing of corpus luteum. The ratio of luteal cells and lysosome increased in the forming luteum. Lipid droplets decreased in the forming stage, and then increased, finally decreased again. The smooth endoplasmic reticulum also increased, but then dilated and regressed. Gap junctions were the main type of junction in the luteal cells. There were numerous endothelial cell with fenestras in corpus luteum.4. To observe the ultrastructure of follicles. The granulose cells in the growing and antral follicles mainly contained endoplasmic reticulum. mitochondria, single free ribosomes, golgi complex, lipid droplets and abundant microfilaments. Granulose cells had more gap junctions, less desmosomes and tight junctions, rare adhere junction. The follicular theca mainly composed of fibroblasts and steriod-secreting cells. The former contained abundant rough endoplastic reticulum, the later contained smooth endoplastic reticulum. Desmosomes were the main type of junction in the theca...