Morphological distinction between filaments that converge upon desmosomes and those that are attached to hemidesmosomes in the epidermis of anuran larvae and lampreys.

Two populations of morphologically distinct intermediate filaments which are segregated into different compartments of the cytoplasm and which may attach to different junctional specialisations were observed in the basal layer cells of the epidermis of tadpoles of Rana catesbeiana, Rana temporaria, Bufo bufo, Leptodactylus flavopictus and Pseudis paradoxus and in the skin of the adult lamprey, Lampetra planeri. These two distinct populations of cytokeratin intermediate filaments were recognised on the basis of their diameter: the thicker intermediate filaments apparently attach themselves to hemidesmosomes whereas the thinner intermediate filaments apparently converge upon desmosomes, in a single cell. The fact that these findings were consistently observed in all the tadpoles of the five species examined and in adult lampreys, and also fit with data for newt larvae, argues in favour of the existence of a uniform structural pattern of distribution of morphologically distinct intermediate filaments in basal layer cells that is a general phenomenon in the epidermis of amphibian larvae.