Fine structure of the integumental glands of a termite soldier

The ultrastructure of some integumental glands occurring in the head, thorax and abdomen of K. flavicollis soldiers is described. The secretory units consist of two cells, the canal cell and the secretory cell (this latter filled with secretion granules). A cylindrical and distorted extracellular space, or reservoir, with an irregular outline is lined by short microvilli. The end-apparatus is made up of small overlapping cuticular laminae which in section resemble small wavy rods. The ample distribution of the units has led the authors to consider them dermal glands. Scanning electron micrographs confirm that the glands' activity consists in the secretion of material which then spreads over the surface of the integument. The dissimilar appearance of the secretion granules present in glands of different soldiers suggests that the electron-lucid granules and the granules with fibrils are two completely different secretions at different ages of the animal. The authors do not therefore rule out the hypothesis that these integumental glands may later produce or release pheromones.