Transport of peroxidase through the midgut epithelium of Glossina M. Morsitans (diptera, glossinidae)

The peritrophic membrane (pm) of teneral female tsetse flies, Glossina morsitans morsitans, did not extend to the full length of the midgut 1-12 hr after emergence. The ingested blood did not reach the posterior part of the midgut (p-part), and the crop still contained food 12 hr after feeding. In these flies, the p-part contained the remains of the larval gut, the meconium, and bacteria. Ferritin molecules fed to tsetse females together with human serum were only found in the endoperitrophic space of the gut. This electron-dense tracer did not penetrate and cross the pm. On the other hand, ingested peroxidase passed the pm, and was transported through intercellular clefts, the basal labyrinth and the basal lamina to the hemolymph. This uptake was observed in the anterior part and to a smaller extent in the middle part of the midgut within 2 hr after feeding. Peroxidase was incorporated from the hemolymph into fat body cells, where it was found 2 hr and later after feeding. Pinocytosis of the tracer molecules, as an additional intracellular pathway to the intercellular route of transport, could not be demonstrated.