ULTRASTRUCTURAL STUDIES OF THE PROVENTRICULUS AND STOMODEAL VALVE OF A TERMITID WORKER (ISOPTERA: TERMITIDAE)

The histological structures of the proventriculus and stomodeal valve are investigated by the transmission electron microscope. The wall of the proventriculus is folded forming 48 folds varies in size and thickness of intima. There are 6 primary-, 6 secondary-, 12 tertiary- and 24 quaternary-folds. Each fold formed of a folding layer of epithelial cells and a denticulated intima except the quaternary folds which are spicules in structure, emerged in between each two successive folds. The size of the folds is increased gradually reaching its maximum size at the mid length of the proventriculus then gradually diminished until complete disappearance except the primary folds which dramatically increased in size occupying most of the proventriculus lumen especially at the part of the proventriculus extended into the stomodeal valve. The wall of the valve formed of a fold of the most posterior part of the stomodaeum. The valve is extended into the most anterior part of the mesentron. The epithelial cells of the proventriculus and stomodeal valve are interdigitated at the side resting on the basal lamina and have cytoplasmic processes towards the intima. The nucleus is comparatively large in size occupying the undigitated part. The interdigitated spaces are in direct contact with the haemocoel through the connective tissues and muscle layers.