An electron microscopic and cytochemical study ofLeptomonas samueli

The fine structure of promastigotes ofLeptomonas samueli is described. This protozoan revealed several features in common with other trypanosomatids. A large membrane-bound cavity containing many vesicles was observed near the nucleus. Pinocytotic vesicles were seen arising from the membrane lining the flagellar pocket. They are associated with some microtubules which originate in the flagellar pocket region and extend toward the multivesicular structure. Morphometric analysis made on electron micrographs showed a mitochondrial relative volume of 0.11 and a peroxisome relative volume of 0.08. Determination of the number of sub-pellicular microtubules in different regions of the protozoon body show that the largest number is found in the region containing the Golgi complex. Carbohydrates were detected using the periodic-acid-thiosemicarbazide-silver proteinate technique. Reaction products were seen in the plasma membrane, in the membrane of the Golgi complex, and in the membranes which form the multivesicular structure. Two cytochemical methods were used to locate basic proteins. Using the ammoniacal silver method reaction products were seen only in the nucleus. With the ethanolic phosphotungstic acid method reaction products were seen in the microtubules which form the flagellum, in the peroxisome-like organelle, and at the region of adhesion of the flagellum to the cell body.