| Cashmere is one of the softest, warmest, finest material for textile = Combination the morphologic character, research on the mechanism of cashmere growth, elucidate the physiology and genetics foundation of cashmere growth on the molecular level, not only having the important meaning in the foundation theories, also in cross breeding and the artificial adjusts to control the cashmere growth provides dependable science theories.The skin is rapidly of differentiation and proliferation in the embryo period of goat. Only have a single cell layer in epidermis on 40 days after pregnancy, the complete epidermis construction form on 75 days. The dermis divides into the papilla and reticular layer gradually on 85 days after pregnancy. Skin construction is stable from 120 to 135 days after pregnancy. The placodes of primary hair follicle firstly appear on embryo midflank skin on 55 days, then the hair follicle grows down into the dermis and the dermal condensate remains as a discrete structure, or prepapilla, that maintains its position at the base of the extending follicle plug. Secondary hair follicle is derived from branches of primary hair follicle, rather than initiation from the epidermis . Hair growth from primary hair follicles on the age of 95 days, cashmere growth out of skin on the age of 105 days, cashmere growth out of skin on the age of 115 days. The follicle population was largely composed of primary trio groups, the S/P ratio was 0.2~5.99:l.The genesis of the primary hair follicle concentrates primarily on 65~85 days, and of secondary hair follicles have a high peak of the time from 95 to 140 days. The direction of hair follicles growth and location of the secondary hair follicle are obvious polarity.The hair follicles enter into pro-anagen from May to August gradually. The new pro-anagen follicles rebuild from old hair follicles. From August to December, they enter into anagen. Most of them enter into catagen in January. The period from February to April is their telagen. The follicle depth is most deep in August, the hair papilla breadth is widest also in August. Epidermis became thicker in April and decline in October. In catagen, the secondary hair follicles still is active, but the cashmeres grow slowly. In telagen, hair follicles lose their activity and the cashmeres no longer grow. The secondary follicle papillas are flat, dermal papilla cells (DPC) sinks inside in anagen, hair papilla is sharp in catagen and telagen, DPC is outward. The result show that the cashmeres grow out of skin earliest in June, they grow fast in October. The time of cashmere growing out of skin is different individually in same species, even different at different part in the same individual. Cashmeres grow out from hip firstly, then on the back of the body, finally from midflank.We constructed a cDNA library with mRNA from skin of 105 days' embryo. Analyzed 846 ESTs, Their average length is 443.2 bps. Five hundred twenty five known genes are identified, they can be divided into cell division (18), cell signal (65); cell construction (73), cell defense (21); gene/protein expresses (126); metabolize (69) and unclassed (153). Wnt-4, BMPR-IB, ASEP gene and Ectodysplasin A are discovered that are important candidate genes for the hair follicle development.Another cDNA library was also built using RNA extracted from the skin tissue from an adult goat. 392 redundancy ESTs, they were registered in the GenBank, GenBank Accession numbers are CD051766-CD052157, and 319 known function gene are identified based on sequence similarity, among them, unidentified is 108, gene/protein expression is 70, metabolism is 43, involved in cell structure is 45, cell signaling/cell communication is 30, cell defence/immunity is 15 and cell division is 8.Some important candidate genes that possibility involved in cashmere growth are TGF binding protein, the EDRK enriched factor, growth factor receptor, G protein associated receptor, dermal papilla derived protein 2, homeobox gene otx2, kallikrein7, jagged-1, thrombospondin-1 andp53.Twen...
|
PDF Full Text Request