The Experiment Research Of Expressions Of Collagen â… , Collagen â…¢ And Vimentin And Changes Of Ultrastructure In Fetal Skin

Objective:To explore the relationship expressions of collagenⅠ(Col-Ⅰ), collagenⅢ(Col-Ⅲ) and vimentin(Vim) and the changes of ultrastructure in fetal skin at different developmental stages and their significance on the process of fetal skin scarless healing. Method:(1) Preparation of animal model:The grown-up health SD rats mated 1:1 and observed vaginal plug at 8:00 in the morning, The day that vaginal plug was found was recorded as gestational age 0 day. After successful mating, female rats were randomly bred to gestational age 10 days,12 days,14 days,16 days,18 days. That is to say, pregnant rats were randomly divided into the five groups. (2) Preparation of tissue samples:Pregnant rats in each group were anesthetized at different gestational age and cut the fetal hip and back skin into three pieces of lmm3 with double-sided blade and placed in 2.5% glutaraldehyde at 4℃for TEM analysis. Under the transmission electron microscope JEOL-1400, it was observed that the ultrastructural changes of epidermis and dermal fibroblasts; The rest of the organization that was cut into pieces of about 0.5 cm-1.0 cm in size was fixed with 10% neutral formalin and made paraffin embedded section, then did the following detections:①The structure characteristics in fetal skin at different developmental stages were observed by HE staining;②The expressions of Col-Ⅰ, Col-Ⅲand Vim in fetal skin at different developmental stages were detected by immunohistochemical staining with SABC method. Each slice was observed, analyzed and photographed with low times (100 times) and high times (400 times) of OLYMPUS’s Ax-70 Imaging System. The average optical density and the number of positive cells in dermis of Col-Ⅰ, Col-Ⅲand Vim were detected with the Image-Pro Plus 6.0 imaging analyze system. (3) The statistics were presented as mean±standard deviation (χ±s) and performed using SPSS 13.0 statistical software. Comparisons between groups were tested by One-Way ANOVA analysis and LSD test. Pearson Correlation Analysis were performed in this study. Results:(1) Col-Ⅰexpression:Expression of Col-Ⅰincreased with the increase of gestational age. Image analysis showed that:the average optical density of G10 was the lowest, with the increase of gestational age, the average optical density increased gradually, the average optical density of G18 increased to the highest. There were significant differences among all the groups (P<0.05); The number of positive cells in dermis gradually decreased with the increase of gestational age. There were significant differences among all the groups(P<0.05). (2) Col-Ⅲexpression: Expression of Col-Ⅲin fetal skin decreased with the increase of gestational age. The average optical density of G10 was the highest among all the groups and gradually decreased with the increase of gestational age, There were significant differences among all the groups (P<0.05). The number of positive cells in dermis gradually increased with the increase of gestational age. There were significant differences among all the groups (P<0.05). (3) Vim expression:The average optical density of Vim gradually decreased with the increase of gestational age, there were significant differences among all the groups except between G10 and G12, G16 and G18 (P<0.05). The number of positive cells in dermis gradually increased with the increase of gestational age. There were significant differences among all the groups (P<0.05). (4) There were negative correlations between Col-Ⅰand Col-Ⅲ, Col-Ⅰand Vim in average optical density and the number of positive cells(P<0.05); There were positive correlations between Col-Ⅲand Vim in average optical density and the number of positive cells(P<0.05). (5) Ultrastructural changes:Epidermal cells in each layer were clearly visible and the number of layers gradually increased with the increase of gestational age, the numeber of rough endoplasmic reticulum and mitochondria in the cytoplasm of fibroblasts gradually decreased with the increase of gestational age. Conclusion:(1) Differences of expressions of Col-Ⅰ, Col-Ⅲin fetal skin at different developmental stages, especially the high expression of Col-Ⅲand low expression of Col-Ⅰin prometaphase gestational fetal skin, was closely related with scarless wound healing. (2) The expression of Vim gradually increased with the increase of gestational age and it might play an important role in scarless wound healing. (3) The numeber of rough endoplasmic reticulum and mitochondria in the cytoplasm of fibroblasts gradually decreased with the increase of gestational age. (4)The phenomenon of scarless wound healing that in prometaphase gestational fetal skin appears is closely related with the unique structure and function of fibroblasts, the expression of Col-Ⅰ, Col-Ⅲand Vim and related gene.