| In order to study the development law of goats skin, expressional significance of integrinβ1, epidermal growth factor and epidermal growth factor receptor during the process of growth. Furtherly to elucidate the molecular regulation mechanism of development of epidermic stem cell and cell factors during the process of skin growth. Skin of goat fetus, aged from 6-18 weeks, were selected in this research. Paraffin section, H-E staining and Masson trichrome staining were selected to study the developmental change of skin morphological structure during growth. Furthermore transmission electron microscope was used to examine the ultrastructural characteristics of different developmental stage of fetus's skin. Immunohistochemistry technique was applied to study the distribution and variation discipline of integrinβ1, EGF and EGFR in the skin's development. Results are as follows:1. Surface of skin was flat and characterized as simple squamous epithelium from 6 to 7th week. Simple columnar epithelium appeared at 8th week. Epidermis proliferated into surface layer and germinating layer at 9th week, which was linked to mesenchyme by basal lamina. In the 10th week, epidermis was divided into three layers including surface layer, stratum intermedium and germinating layer, in addition, dermis appeared at the same time, which contained a little collagen fiber and elastic fiber. Hair bud formed in the mesencyme, which come from round solid cell mass in some parts of dermis. Till 11th week, epidermis continues to proliferate, with which little tonofibril and Langerhans cell appeared in the germinating layers. Hair follicle and eccrine sweat glands also can be observed. Epidermis cell differentiate into cuticular layer, stratum lucidum and stratum granulosum in the 12-13th week. Eccrine sweat glands and papillary layer formed obviously, with lots of collagen fiber in the dermis. From 14 to 15th week, the tonofibril increased and thickened, and typical structure of desmosome formed. Epithelium cells of hair bulb differentiate into external root sheath, primodium of internal root sheath and prosoma of hair; sebaceous gland and arrector muscle can be seen at two sides of hair follicle. The amount of collagen fibers located in deep layer of epidermis continued to increase. Many sections of sweat glands and secretory portion also can be seen. From 16 to 17th week, epidermis layer became thin, and hair formed which can stretch out the body gradually. Collagen fibers and elastic fibers in dermis increased greatly which made the dermis thickened obviously. After 18 week, skin and its derivates developed continuously till consummate in structure.2. Low expressions of EGF and EGFR appeared at the sixth week. Afterwards, the expression of EGF and EGFR increased as the fetus growed. Before the 11th week, EGF positive reaction mainly located in cytoplasm of basal layer cell of epidermis, hair follicular epithelium cell and collagenoblast, and then EGFR mainly located in cell membrane of correspoinding cells. From 11-16th week, the expression of EGF and EGFR not only located in basal layer cell of epidermis, prickle cell layer, hair follicle cell of dermis and collagenoblast, but also in endothelial cell of blood vessel, epidermic cell of sweat gland and arrector pili muscle. EGF mainly distributed in the cytoplasmic of those cells, and EGFR in the membrane of those cells. From 17th week to birth, EGF mainly located in basal layer cell and epithelial cell of hair follicle as the skin thinned, and the positive reaction continue to increase.3. In the 8th week,β1-integrin positive reactions was distributed weakly in the epidermis, they mainly occured in cytoplasm of deeper level cells of epidermis from 9 to 10th week.β1-integrin can be examined in each layer of epidermis from 11 to 13th week. During 14 to 16th week, distribution range ofβ1-integrin enlarged to eminence area of hair follicle, epidermic cell of external root sheath and sweat gland, and the positive reaction deadened gradually. After 17th week, distribution ofβ1-integrin in epidermis only distribured in parts of stratum basale, and the number of positive cells decreased in other parts. But in the eminence area of hair follicle and external root sheath, the expression ofβ1-integrin continued to strengthen.
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