Specialization of the hindgut wall for the attachment of symbiotic micro-organisms in a termite Procubitermes aburiensis (Isoptera, Termitidae, Termitinae)

The posterior colon of worker-caste termites accommdates an abundant, heterogeneous population of procaryotic organisms which are retained by attachment to prominent cuticular spines elaborated from the gut wall. The spines extend to nearly one half the diameter of the lumen and are each supported by a specialized root cell in which bundles of parallel microtubules traverse the cytoplasm from the apical to the basal surfaces. Additional epithelial cells are present which show infoldings of the apical plasma membrane and are overlain by cuticle containing deep, vase-shaped pits opening to the gut lumen. It is proposed that the root cells are designed to resist shearing forces transmitted to the base of each spine during contractions of the gut. The cuticular pits may represent sites of permeability to the end products of microbial metabolism.