Determination of Secondary Follicle Characteristics, Density, Activity, and Hoxc13 Expression Pattern of Hexi Cashmere Goats Breed.

This experiment was conducted to identify some aspects of secondary follicle (SF) characteristics of Hexi cashmere goats at five different growing stages in one year in order and discover the expression pattern of Hoxc13 in a SF cycling to provide morphological basis for studying the growth of cashmere. Ten cashmere goats of one-year old (5 males, 5 females) were included in this study. The density and activity of SF were observed and measured by making paraffin sections, the ultra-structural features of SF were studied under transmission electron microscopy (TEM) by making ultra-thin sections, and the expression of Hoxc13 was investigated through the immunohistochemistry method. The average diameter of SF had the smallest value in the anagen stage, and significant difference (P < 0.05) was found between the anagen stage and other stages. The density of SF increased gradually through the different growing stages, and significant difference was found between the anagen and procatagen stages (P < 0.05). With an increase in time (months), the percentage of SF activity increased, and significant difference in the percentage of SF activity was found between the telogen and anagen stages (P < 0.05). At the telogen stage, the layers of connective tissue sheath (CTS) of SF were unclear, hemidesmosomes between the outer root sheath (ORS) and basement membrane disappeared, and dead cells were found at the top of the SF. The rudiments of new SF were found in the proanagen stage, CTS was thickened, and the cells of ORS were stretched out like fingers. At the anagen stage, the structure of SF was integral, and the inner root sheath (IRS) consisted of three concentric layers (Helen, Huxley, and Cuticle layers). The cells of Huxley's layer degenerated gradually, and pseudopodia were formed on the cells of ORS in the procatagen stage. At the catagen stage, the ORS was separated from the IRS, and IRS disappeared. Huxley's layer was absent in the inactive SF while, the ORS was present in the active SF. Hoxc 13 was expressed in the epidermis and sebaceous gland o, ORS, IRS, hair shaft of SF in the skin. Hoxc13 was expressed weakly during procatagen, catagen, and telogen stage, while with an increase in proanagen and anagen stage, significant difference was found between them. These findings demonstrated the ultra-structural features of SF could provide the useful activity criteria, and Hoxc13 associated with the SF activity.