Reticular and collagen fiber characteristics in human bone healing

Abstract

1. 1. A preliminary investigation of the histochemical and histologic characteristics of reticular and collagen fiber formation in regenerating bone of the human alveolar socket has been completed. 2. 2. Early bone formation was initiated in highly metachromatic ground substance in which osteoblasts and fibers were observed to be satiated with alkaline phosphatase. At variance with reports of others in animal experimentation, we found the early osteoid in the healing human alveolar socket to be completely negative for alkaline phosphatase except to encircle the lacunae and periphery of the matrix. As bone development progressed, the metachromatic ground substance in the osteoid was replaced by an increasingly positive Schiff reaction. It was further ascertained that during osteogenesis a type of inverse relationship developed in the histologic elaboration of reticular and collagen fibers; reticular fibers were heavily concentrated at the periphery of the developing bone matrix, were sparse within the matrix although manifesting some organization, and rarely projected beyond the matrix border. On the other hand, collagen fibers were only moderately concentrated at the periphery, were heavily concentrated within the matrix but without apparent organization, and usually projected beyond the matrix border into the interstitial tissue. These observations have been summarized in Table I. Comparison of Reticular and Collagen Fibers in Osteogenesis of Human Bone Wounds RETICULAR COLLAGEN 1 Organization of fibers with regard to osteogenesis when found free in young connective tissue Not organized (Figs. 1. and 3) Not organized (Figs. 1 and 3) 2 Organization of fibers with regard to osteogenesis when in contact with and external to developing bone matrix Organized (Figs. 1 and 2) Organized (Fig. 5) 3 Concentration of fibers in contact with and external to developing bone matrix More than in matrix (Figs. 1 and 2) Less than in matrix (Fig. 5) 4 Concentration of fibers within matrix Sparse (Fig. 4) Heavy (Fig. 5) 5 Organization of fibers within matrix Organized (Fig. 4) No apparent organization (Fig. 5) 6 Fibers from matrix project beyond border Rare (Fig. 1, B) Usual (Fig. 5) 3. 3. A functional orientation has been observed in the uniform behavior of both reticular and collagen fibers in external contact with the developing bone matrix. They have consistently been observed to point in the direction of most active bone regeneration, which in this case was the central area of the socket fundus. Both the reticular and collagen fibrils have been observed to align themselves parallel to each other and to develop, therefore, identical angulation with the matrix border of the developing bone with which they are in contact. It is our contention that the tendency of these fibers to orient toward the area of most active osteogenesis determines their angulation with the border of the developing bone. Reticular and collagen fibers found peripheral to the bone were proved not to manifest any apparent degree of organization with regard to osteogenesis.