[Ultrastructural study of human pulp cells cultured in vitro].

Primary cultures from human dental pulp were produced in Leighton tubes in the compound nutritive medium of Eagle consisting of calf serum, ascorbic acid, penicillin and streptomycin. After 2 months, the coverglasses supporting the cultures were recovered and fixed for electron microscopy. The results obtained showed a polarisation of the cells, the presence of a cilium, a highly developed endoplasmic reticulum, a typical Golgi apparatus with coated vesicles in the vicinity, elongated dense secretion vesicles containing a cross-striated filamentous material, numerous mitochondria, microfilaments with thickenings, microtubules, secretion granules, multivesicular bodies and electron dense structures united by a fibre with a periodic cross-striation of 640 A. These cells secreted a collagenous matrix uith an at random fibrillar distribution, fusiform outlines of fibrils (diameters varying from 650 A to 3,600 A), a cross-striation of 640 A and the presence of electron dense zones on the fibrils. "Globules" (with a trilamellar membrane of about 110 A) were identified in the extracellular medium. The possible comparisons between the typical characteristics of these cells and those of the odontoblast and pulpal fibroblasts were discussed.