[Ultrastructural demonstration of the phagocytic activity of periodontal ligament fibroblasts in the rat using enzymatic tracers].

The ultrastructural study of non-decalcified periodontal ligament of rats, labeled with horseradish peroxidase used as an enzymatic tracer for the mechanism of endocytosis, shows that there exists in the fibroblast, on the one hand, an endogeneous peroxidase revealed by the preparation and characteristic of certain cellular organelles: mitochondria, free ribosomes, ribosomes of the granular endoplasmic reticulum; and on the other hand an exogeneous peroxidase which demonstrates the ability of fibroblasts to phagocytose. This exogeneous peroxidase initially marks the collagen fibrils located in the extracellular medium, then at a later time he cytoplasmic membrane during its invagination, and finally the membrane of phagosomes. The intracellular collagen situated at the interior of phagosomes is also marked by the peroxidase and demonstrates the passage of the collagen from the extracellular medium to the intracellular medium.