Horn Morphogenesis And Expression Of SHH And β-Catenin In Bos Grunniens Horn

Ed60～240 to o.5～5y male Yak horn placode skin and same age cattle horn skin were used as material test and control material respectively to investigate horn morphogenesis.The pararrin embed tissue section was stained by H.E method for studying the histomorphogenesis changes and EnVision immunohistochemistry for detecting qualitatively and quantitatively expression of SHH andβ-catenin during horn morphogenesis.Results is following:1. According to the horn keratin sheath and hair follicle occure or not, horn morphogenesis is classed into five stage: horn placode prophase (Ed≤60); horn placode metaphase(Ed60～140).horn placode anaphase(Ed140～250 ). fleshy horn (≤0.5y). horn(≥0.5y).2.Hair follicle morphogenesis in Yak horn placode initiate from horn placode periphery and extendto horn palcode centre gradually,the hair follicle on horn placode skin arranged as votex through oblique angle,and the left horn hair fiber show clockwise, the right horn's is reverse orientation; the hair follicle(Ed240～5y) on horn periphery of the horn undergo regression and apoptosis, then migrate to upper horn epidermis and form keratin sheath by special signaling inducing; dermal papilla of the adult horn top are longer and denser, middle part's are shorter and sparser as well as horn periphery's are denser than the medium.3.SHH andβ-catenin of horn top and periphery during horn morphogenesis in yak show same intense-weak-intense pattern; SHH andβ-catenin expression in horn periphery epidermal basal layer synchronously, the mesenchyme expression is negative,β-catenin expression only in fleshy horn epidermal basal layer; SHH andβ-catenin is non–expression in horn top. SHH andβ-catenin expression pattern in yak and cattle horn is similar.Our results suggest that SHH andβ-catenin cooperate each other and have respective function during Yak horn morphogenesis.We speculate on SHH andβ-catenin may play a key role during epithelial-mesenchymal interaction of horn morphogenesis and the horn periphery hair follicle change into horn keratin layer from horn periphery go through trans-differentiation.