LOCALIZATION AND SYNTHESIS OF COLLAGEN TYPE-III AND TYPE-V DURING REMODELING AND DECIDUALIZATION IN RAT UTERUS

Uteri of pregnant rats on Days 6, 7 and 8 of pregnancy were studied to determine the histochemical distribution of collagen types III and V and the incorporation of [H-3]glycine into fibrillar collagens during the period of embryonic implantation. Types III and V had a similar di stribution in the non-decidual stromal region and muscle layers in imp lantation sites. They were found to have very low levels in the primar y decidual tissue on Day 6 and were not detected in developing decidua l tissues on Days 7 or 8. Following injection of labelled glycine, col lagen was extracted and the specific activity of the collagens determi ned by fluorography and 3H incorporated into the collagen bands in the gels. It was found that incorporation of label into both types I and III was similar (33.4 +/- 12.0 and 31.8 +/- 18.1 cpm mu g(-1) collagen respectively) but 3.5 times that of type V (7.7 +/- 5.3 cpm mu g(-1)) . These studies suggest that although fibrillar collagens are metaboli zed or redistributed in the growing decidual tissue, they are incorpor ated rapidly into the extracellular matrix during remodelling of the o uter stroma and muscle tissues.