Postnatal Sexual Development And Its Relationship With The Estrogen And Progesteron And Their Recepotrs In Female Jining Gray Goats

As a first-class strain in China, the Jining Gray Goat is characterised by early sexualmaturity and high progenitive rate. To study the sexual development of the Jining Gray Goatby investigating its hormone level and receptor expression is of great significance to suchefforts as to elucidate the mechanism for its early sexual maturity and to breed new strains orlines of goats with high progenitive capacity. In this study, the Jining Gray Goat wasinvestigated by means of radioimmunological, histochemical and immunohistochemicalmethods, transmission electron microscope, reverse transcription-polymerase chain reaction(RT-PCR) and Western Blot. The fluctuations of estrogen and progesterone in the blood,age-related distribution changes of estrogen receptors and progesterone receptors in thehypothalamus-hypophysis-ovary axis and in the reproductive organs of the goat from beingborn to sexual maturity were systematically studied on the level of hormones, cells,subcellular fractions and molecules. The study showed after the female goat was born:①ERand PR positive cells were present in reproduction-associated nuclei in the hypothalumus, thenumber of the cells increasing with the goat’s age and positive staining of ERβ being muchstronger than that of ERα（p<0.05） in the same nuclei at the same stage. The age-relateddistribution changes of ERα，ERβ and PR positive cells in the hypothalumus were closelylinked to the goat’s early sexual development and maturity. The distribution and the changerule of PR positive neurons and and that of ERβ are basically identical;②The chromophilcells in the adenohypophysis grew in number and volume with age; ERα was mostly presentin the nuclei of chromophil cells, ERβ and PR in cytoplasm; at puberty (D60), chromophilcells of the pituitary began a growth spurt morphologically with an remarkable increase of theexpression of ERα and ERβ; AOD peak of PR positive cells appeared at D120, when the goatwas sexually mature, and the high expression of PR appeared with the changes of pituitaryfunctions；③The ovary of the goat typically develops fast and matures at an early stage. Thenewborn ewe has growing follicles and high expression of ERα, ERβ, PR and mRNA in itsovary. From0to30days of age, rapid morphological growth was seen, weight and volumeincreased significantly; the boundary between the inner and outer cortex disappeared. Ovarianfunction improved remarkably when the kids were60-90days old. When60days old, the animals began to ovulate, corpus luteum or corpus albicans appeared and the expression ofERα, ERβ and PR and their mRNA significantly increased, which indicated the animalsreached puberty. On day90, the animals manifested sexual maturity, with the biggest maturefollicle6.18mm in diameter; the expression of ERβ and PR protein and their mRNA wasmaintained at a high level, with decreased expression of ERα. Before puberty, the expressionof ovarian ERα (prepubertal dominant receptor) and it’s mRNA was significantly higher thanthat of ERβ (dominant receptor after sexual maturity);④The expression of ERα mRNA, ERβmRNA and PR mRNA was present in the uterus of the goat of different ages. The proteinimmune positive products of ERα, ERβ and PR were located in the nuclei of epithelial cells ofthe uterine cavity, glandular epithelial cells, stromal cells, vascular endothelial cellsand smooth muscle cells. The expression of ERα and ERβ became increasingly strong fromD60, and became strongest at D90. Two peaks of PR appeared separately at D120and D180.The distribution and expression of ER, PR and their mRNA in the uterus of the goat atdifferent postnatal development stages suggested that the goat’s prolificacy was linked to itsexcellent intrauterine condition;⑤ERα, ERβ, PR, FSHR and LHR were present in theepithelium of fallopian tubal ampullae and fimbria tube and these receptors hastime-and-space specific expression in the epithelium of oviduct. Before sexual maturity(D0-D60), the goat’s hypothalamus-pituitary-ovary axis was not mature, there was weakexpression of ERα, ERβ, PR, FSHR and LHR in the epithelium of fallopian tubal ampullaeand fimbria tube, and the intergral optical density of positive cells was low; After sexualmaturity (D90-D180), the expression of ERα, ERβ, PR, FSHR and LHR in the epithelium ofoviduct increased, hormone receptors bound to ligands regulated the differentiation anddevelopment of the epithelium, which increased the number of ciliated cells and secretorycells in the epithelium of fallopian tubal ampullae and fimbria tube; therefore the epithelialcells had more glycogen and mucus and the epithelium functioned more actively. Besides,“cavity discharge” phenomenon was found in the goat aged D150and those older at the freeedge of the epithelium of fallopian tubal ampullae and fimbria tube and the products of“cavity discharge” were holocrine secretory cells.