Fine Structure of an Unusual Intracellular Supporting Network in the Leydig Cells of Amblystoma Epidermis

The early literature of light microscopy was rich in excellent descriptions of the large and beautiful cells of amphibians. The mucous cells of the epidermis of larval salamanders, rarely mentioned in the cytological literature today, received considerable attention in this earlier era. Described by Leydig (1) in 1857, these large, round cells are so common over the body of the larva that in some regions they form a continuous middle layer between the basal cells and the outer cellular layer of the epidermis. They are characterized by the presence of large cytoplasmic granules that give the staining reactions of mucus (see reviews by Heidenhain (2) and Dawson (3)). The ground cytoplasm around the granules appears pale and devoid of visible structure when viewed with the light microscope, but a denser area can be seen adjacent to the nucleus (Fig. 1). Langerhans (4) described a supporting network in the peripheral cytoplasm of Leydig's "Schleimzellen" and early investigators (2) speculated that the shape of this large, rather empty cell was maintained by the rigid, basket-like, peripheral net of Langerhans (Fig. 1). The present study confirms Langerhans' observations of a structure which in its dimensions is at the limit of resolution of the light microscope, and adds several observations of interest to students of the fine structure of cytoplasmic filaments and desmosomes.