Fine structure of the resorptive cells in the teeth of frogs

Abstract

Abstract Teeth undergoing resorption were dissected from the maxillae of frogs and prepared for electron microscopy using standard methods and methods designed to minimize demineralization. The resorptive cells overlapped one another, forming palisades. A central ruffled border was surrounded by a relatively structureless cytoplasmic “seal.” Crystals of mineral were present in the folds of the ruffled borders, and demineralized collagen fibrils were seen in the adjacent matrix in sections treated to prevent demineralization. The surfaces of the cells opposite the ruffled borders displayed numerous small villi. The cytoplasm of the resorptive cells contained a variety of lysosomes in various stages of development, mitochondria, scattered vesicles of endoplasmic reticulum and free ribosomes. Well developed Golgi zones were frequently seen, and occasional sections passed through centrioles. Two centrioles were commonly seen in such sections, but never more. Occasional patches of cytoplasm contained mitochondria and rough‐surfaced endoplasmic reticulum, resembling “blast” cell cytoplasm. We concluded that the resorptive cells of several mineralized tissues of various vertebrates are morphologically, indistinguishable.