Band Densities in Unstained and “Negatively Stained” Collagen Fibrils

Three models for the 3-dimensional organization of tropocollagen macromolecules within the collagen fibril are currently in vogue. While all fairly similar, these models are largely based on, or in agreement with, electron micrographs from collagen stained with the “negative contrast” technique. The purpose of this study was to examine the banding pattern in electron micrographs of unstained collagen fibrils and compare this to the “negatively stained” pattern and to the band densities predicted by the theoretical models. The results indicate that the models need modification and that a revised interpretation of “negatively stained” micrographs of collagen is in order.