Skin glands in the axolotl: the creation and maintenance of a spacing pattern

The morphogenesis of skin glands in the larval axolotl is described at the light microscope level. The glands are derived from the epidermis, but are eventually located in the dermis. The glands are non-randomly arranged within the skin and the spacing pattern tends towards a hexagonal array in two dimensions. Analysis of the spacing pattern in animals of different sizes reveals that a clear relationship exists between gland size and the distance between glands. Occasionally, new small glands are inserted into the pattern, suggesting that the spacing of glands in under a dynamic control throughout the growth of the axolotl. The possible mechanisms underlying the creation and maintenance of the pattern are discussed.