Honeycomb structure in the lamina lucida of epidermal basement membrane during metamorphosis of Rana temporaria ornativentris.

In this study we examine the structure of the lamina lucida during metamorphosis of Rana temporaria ornativentris. During the metamorphosis of anuran larvae, both the epidermal cells and the dermal connective tissues in the tail regenerate. The basal surface of the epidermis becomes irregular and the epidermal basement membrane detaches from the epidermal cells, showing a widened lamina lucida. In this widened lamina we observed a geometrical honeycomb structure and a ladder structure. Each side of the honeycomb structure was approximately 40 nm and the intervals of the ladder structure were approximately 50 nm. From our observations we believe that the honeycomb and ladder appearances are different aspects of the same structure. At the beginning of metamorphosis anchoring filaments were prominent in the lamina lucida and, when the lamina lucida was tangentially cut, the lamina lucida showed the honeycomb structure. These results suggest that both the honeycomb and the ladder structures observed in the widened lamina lucida originate from constituents of the lamina lucida and become morphologically evident during the epidermal-dermal separation.