Abstract: 【Objective】This study aims to research the organizational structure of China Super-Fine Merino hair follicles and hair follicle morphogenesis process, which will lay a histological basis for molecular regulation mechanism of Super-fine Merino hair follicle development.【Method】Tissue frozen section was conducted by embryonic skin of China Super-Fine Merino and the results were taken photography under a microscope.【Result】Results showed that the follicle structure of Super-fine Merino sheep consists of connective tissue sheath, outer root sheath, inner root sheath, hair shaft and hair bulb sections, as other mammals. Primary hair follicle occurred on 87th day of fetal period, vesicle structure of the secondary follicle could be found at the bottom of the primary hair follicle. At gestational 138 d, the primary basic hair follicle was mature. From gestational 87 d to 147 d, the density of primary follicle was gradually decreased and the density of secondary follicle was increased as the gestational age growing, meanwhile the density of primary follicle reached its maximum value (232.8±12.44) (per mm2) at gestational 117 d. The gestational Secondary Follicles to Primary Follicles ratio (S/P ratio) reached the maximum (9.96) at gestational age 126 d.【Conclusion】Primary follicles began to occur at 84 d of gestational age, and secondary hair follicle began to occur at 87 d of gestational age, gestational age 102 d in the original the secondary follicles neck bulge began regeneration to secondary-derived follicles, most of primary follicles and some of secondary hair follicle had matured. The differentiation of secondary hair follicle is a key factor which affected the density of hair follicle; it can effectively increase the density of hair follicle and improve the quality of the wool.

Key words: China Super-Fine Merino (Gansu type) , hair follicles structure , morphogenesis , secondary-derived follicles , S/P ratio