[Ultrastructural study of the cellular cementum in rats]

The study of the cementum of adult rat molars has essentially shown resting and developing surfaces. The resting cementum surface is covered by fibroblasts oriented perpendicular to the surface and surrounded by collagen bundles entering perpendicularly in the cementum or oriented parallel to the surface. On the surfaces with apposition, cementoblats and cementoid cementoblasts, becoming finally cementocytes, were observed. A decrease in cytoplasmic organelles is noted in these latter cells when going from the surface to the cementum depth. An organic pericementocytic space is located between the comentocyte cytoplasmic membrane and the lacunar calcified wall. In the interlacunar tubules, tight and gap junctions were present between the cytoplasmic processes of adjacent cells. Groupings of several epithelial-like cells were embedded in large intracemental cavities. They probably correspond to epithelial rests of Malassez.