Studies On Developmental Changes Of Hair Follicle And Differential Expressions Of MTR-1A,IGF-1 And TYR Genes In Jining Gray Goat Skins

To reveal the developmental changes of hair follicle and cytokines effected on the differentiation of hair follicle in Jining Gray goat skins. The tissue slice methods were used to study the skin and hair follicle structures at different stages; and real-time quantitative PCR technique was applied to detect the MTR-1A, IGF-1 and TYR mRNA expressions of skins. The main results are as follows:The histology methods and micro-observation approach were used to compare the characteristics of skin and hair follicle structures of Jining Gray goats within 85-days fetus, 3-days-old, 1-month-old, and one-year-old.(1) 85d fetal skin epidermis differentiated into three layers and thickening, dermis divided into upper and lower levels, interlacing with fibroblasts. Secondary follicle placode can be found in the cuticle. All placodes of primary follicle in fetus had formed before birth, placodes of secondary follicle were decreased with the birth to 1 month and developed into wool fiber.(2) In kid-skins, collagen fibers in follicle layer were interlaced level while in the plexiform layer parallel intertwined. Elastic fibers in follicle layer were thin and curved interwoven arrangement while reticular layer of inelastic fibers distributed. The numbers of primary follicles were larger than secondary follicles. The density of hair follicle was smaller. Hair folliculus group was made up from 2-3 primary follicle and 1-2 secondary follicle.(3) In lamb-skins, follicle and reticular layer were thickening with collagen fibers. Hair folliculus group was made up from 1-5 primary follicles and several secondary follicles and the most of follicle groups were three.(4) In adult-skins, the thickness follicle layer contained more connective tissue, collagen and elastic fibers was larger than reticular layer's. Adult medullary primary follicle was large with sebaceous glands and other accessory structures around distributed; secondary follicle without medulla and hair bulb was small. Hair folliculus group was same with lamb.(5) In different parts of adult-skins, epidermis, derma, follicle layer and reticular layer thickness of cervical skin were larger than back's, abdomen's were the smallest, there was extremely significant difference between cervical, back and abdomen; wool density of adult back skins was larger than other positions (P>0.05); different parts of wool fineness were no significant difference; abdomen follicle groups diameter was larger than back's, buttocks'was the smallest (P<0.01); cervical primary and secondary follicles depth were deeper than back's, buttocks'was the smallest (P>0.01).Real-time quantitative PCR was used to study MTR-1A, IGF-1 and TYR mRNA expressions in skins of Jining Gray goats within 85-days fetus, 3-days-old, 1-month-old, and one-year-old.(1) MTR-1A and IGF-1 in lamb-skins were extremely larger than other developmental phases, 19.5 and 39.26 times than fetus. MTR-1A and IGF-1 largely mRNA expressions in lamb-skins indicated that they played a role in promoting the development of secondary follicle.(2) MTR-1A expressed in one year old adult cervical and back skins were different with buttocks (P<0.05).IGF-1 expressed in cervical, back and buttocks skin were larger than abdomen (P<0.05). MTR-1A and IGF-1 differential expression and distribution of hair follicle group indicated MT play an important role in primary hair follicle than IGF-1.(3) MTR-1A and IGF-1 differential expression related with wool fineness (P>0.05), they are important candidate genes effecting wool fineness.(4) TYR mRNA expressed in kid and adult-skins were significant larger than lamb-skins', because of lighting the main activity of the skin was the occurrence of melanin granules after birth, melanocyte at the top of the dermal papilla generated melanin granules effecting the colour of wool fiber.The results lay the foundation to reveal the developmental pattern of Jining Gray goat's hair follicle. Furthermore, these results also reveal the genetic mechanism of Jining Gray goat's pattern quality.