Comparison of collagen types in adult and fetal bovine corneas

The collagen types in the fetal and adult bovine corneal layers were compared. The cornea was separated into epithelial, endothelial, and stromal layers. Of the interstitial collagens, type I was the predominant in all layers of both fetal and adult corneas. Only type I of the interstitial collagens was found in the three layers of the adult cornea. Type I collagen was also found in all layers of the fetal cornea together with a minute amount, less than 2%, of type III collagen. The type III collagen could only be detected by cyanogen bromide peptide gel maps and was not apparent by gel electrophoresis of intact alpha chains. Of the noninterstitial collagens, type V was present throughout the three corneal layers. Type IV, basement membrane-specific collagen was found only in the endothelial and epithelial layers, which contain Descemet's and Bowman's membrane, respectively. The transient presence of type III collagen reflects an embryonic stage of corneal development.