Immunohistochemical study of type III collagen expression during pre and post-natal rat skin morphogenesis

Skin extracellular matrix, which contains type I and type III collagens, is involved in skin development. The aim of this study was to investigate type III collagen distribution pattern as well as its changes during pre and post-natal skin morphogenesis in rats. Ventral skins of Wistar rat embryos at different stages from 10 to 20 gestational day (E10-E20) and also one month and one year post natal rat pups were fixed in normalin, embedded in paraffin and 5 µm thick sections were incubated with Anti type III collagen antibody. In order to detect staining intensity, the reactions were observed and graded by three examiners separately. Kruskal-Wallis non-parametric statistical test and SPSS software version 11.5 were used to compare differences between samples. Immunoreactivity of type III collagen was distributed weakly in the mesenchymal connective tissue on day 10 (E10). The observed reaction was increased onE12 and E14. This reaction was clear in basement membrane, relatively intensive in dermal papillae and moderate in dermal reticularis on E14. This immunoreactivity pattern was increased afterward on E16, not changed on E18 and decreased in dermal reticularis on E20. The density of collagen type III in dermal papillae and dermal reticularis in skin of one year old rats were decreased comparing to one month old rats. Our results showed that type III collagen is expressed and timely regulated during pre and post natal rat skin morphogenesis.