Chemical and morphological studies on inorganic phosphate deposits in Rana catesbeiana skin

Skin from Rana catesbeiana adults and tapoles was found to contain an unusually high concentration of inorganic phosphate which was chemically identified and histologically localized as dense granules of calcium phosphate deposited as a discrete layer at the junction between the stratum spongiosum and the stratum compactum of the dermis. Electron microscopic studies revealed that the granules were composed of fine needle‐like crystals and were not associated with cells which seemed obviously related to their genesis. Although no definite function was established for this apparently normal structure of bullfrog skin, its possible role as a reservoir of readily available calcium was suggested. As such, it would represent an important factor to be considered in studies of the biochemistry and physiology of frog skin, especially those which deal with the effects of calcium depletion.