Objective:To observe the localization and expression characteristics of alpha-smooth muscle actin (AS-MA),basic fibroblast growth factor (bFGF),epidermal growth factor (EGF),transforming growth factor-β(TGF-β) isoforms,and their receptors in fetal and adult skins in order to explore their potential biological significance.Methods;The expression and the distribution of ASMA,bFGF,EGF,TGF-βisoforms,and their receptors were de-tected with immunohistochemistry and histopathology methods in 36 skin specimens.Among them,30 specimensbelonged to fetuses at different developmental stages and 6 were from adults.Results:Positive immunohistochemicalsignals of ASMA,bFGF,EGF,and TGF-βisoforms and their receptors could he found in fetal and postnatal skins.These factors were mainly distributed in the cytoplasm and extracellular matrix of epidermal cells,endothelial cells,hair follicle epithelial cells and some fibroblasts.Receptors of these factors were mostly located in the cellular mem-brane of the above mentioned cells,while protein particles of ASMA could be observed in myofibroblasts and sweatgland cells.Along with ascent in gestational age,the positive cellular rates of bFGF,EGF,TGF-βisoforms,theirreceptors,and ASMA in skin were elevated progressively.In skins specimens obtained from fetuses of late-trimester(29-31 week gestation) and adult,the positive rates of these proteins were significantly raised in comparison withskin of fetuses of early-trimester.Conclusion;The endogenous bFGF,EGF,three TGF-βisoforms and their recep-tors might be involved in the development of the skin in embryonic stage and in the cutaneous structure and function,and also wound healing in adult stage.The relative lack of these factors and their receptors might be one reason whythe wound of fetus heal by regeneration rather than by scarring. Objective: To observe the localization and expression characteristics of alpha-smooth muscle actin (AS-MA), basic fibroblast growth factor (bFGF), epidermal growth factor (EGF), transforming growth factor- beta receptors in fetal and adult skins in order to explore their potential biological significance. Methods; The expression and the distribution of ASMA, bFGF, EGF, TGF-beta isoforms, and their receptors were de-tected with immunohistochemistry and histopathology methods in 36 skin specimens. Among them, 30 specimensbelonged to fetuses at different developmental stages and 6 were from adults. Results: Positive immunohistochemicals of ASMA, bFGF, EGF, and TGF-βisoforms and their receptors could he found in fetal and postnatal skins.These factors were mainly distributed in the cytoplasm and extracellular matrix of epidermal cells, endothelial cells, hair follicle epithelial cells and some fibroblasts. Receptors of these factors were mostly located in the cellular mem-brane of the above mentioned cells, while protein particles of ASMA could be observed in myofibroblasts and sweatgland cells. Along with ascent in gestational age, the positive cellular rates of bFGF, EGF, TGF-beta isoforms, their receptors, and ASMA in skin were elevated progressively. In skins specimens obtained from fetuses of late-trimester (29-31 week gestation) and adult, the positive rates of these proteins were significantly raised in comparison with skin of fetuses of early-trimester. Confc; The endogenous bFGF, EGF, three TGF-beta isoforms and their recep-tors might be involved in the development of the skin in embryonic stage and in the cutaneous structure and function, and also wound healing in adult stage. the relative lack of these factors and their receptors might be one reason why the wound of fetus heal by regeneration rather than by scarring.