Trypanosoma congolense: Fine structure study by the carbon replica and freeze-etch technique

Abstract

The fine structure of the blood parasite. Trypanosoma congolense was examined by the carbon replica and freeze-etch techniques. The ultrastructure of the limiting cytoplasmic membranes and the limiting membranes of constituent organelles was examined. The pellicle complex was shown in a three-dimensional view. The parasites' outer pellicle layer was smooth and regular and lacked any obvious subunit structure. The inner limiting membrane around the body of the parasite was shown to be coarse and irregular and lacking in any obvious subunit structure. The appearance of this portion of the unit membrane of the pellicle complex differed considerably from the appearance of the membrane which surrounded the flagellar apparatus. The flagellar membrane had a uniform stippled appearance. It appeared to be made up of the “brick-like” subunits, regular in size and shape. In general the membrane of the mitochondrion also had a uniform stippled appearance. The membrane of the kinetoplast portion of the mitochondrion, however, differed from the membrane of the other portions of that organelle in that it had a regular pattern of pits in its surface. Nuclear membranes were characterized by a highly rough and irregular appearance. Nuclear pores occurred in the nuclear membranes. However, unlike those of Plasmodium gallinaceum and chicken erythrocytes, their size, shape, and distribution were irregular.