An electron microscopic study of collagen formation in the dental pulp of the human premolar and rat incisor.

Collagen secretion and maturation were investigated at the ultrastructural level. Pulp tissue from the continuously growing incisor of the rat provided excellent material for studying the secretory aspects of the tropocollagen. More mature human pulp material proved valuable in viewing the collagen fibril. A networklike arrangement of fibroblasts and fibrocytes was noted. Various types of cell junction were found in all specimens. The finding of a nexus junction was particularly interesting. It is hypothesized that connected cell systems rather than single cells might be the functional units involved in collagen formation.