Diameters of Collagen Fibrils grown in vitro

Abstract

THE aggregation in vitro of purified collagen from solution into native-type fibrils, each of typically uniform cross section and showing the characteristic 640–700 Å axial periodicity, has been extensively studied (for reviews see Wood¹, Ramachandran²). We studied the growth of fibrils in sodium phosphate buffer at pH 7 turbidimetrically and morphologically by taking samples for electron microscopy at various known stages of precipitation. Although a broad range of fibril diameters was observed at all stages, the distribution was found to exhibit no significant change after less than one quarter of the collagen had precipitated. It is inferred that, once a collagen fibril has grown to a diameter somewhere in the range 600–2,400 Å, lateral growth ceases and the fibril grows only at the end regions where the diameter is smaller.