MONOCERCOMONAS SP - CYTOCHEMISTRY AND FINE-STRUCTURE OF FREEZE-FRACTURED MEMBRANES

Monocercomonas sp. from the wood-snake Tropidophis melanurus was studi ed using fast freezing of alive and fixed cells followed by freeze-fra cture and deep-etching. Cytochemistry for enzymes (acid phosphatase, n eutral phosphatase, and thiaminopyrophosphatase) and for carbohydrates and endocytosis of gold-labeled albumin were also performed. The Golg i complex is formed by 12-14 cisternae with typical cis and trans face s connected to a network of tubular and cisternal structures, and is p ositive for thiaminopyrophosphatase at the trans face. Intraluminal fi lamentous structures are seen connecting the two faces of the cisterna e of the Golgi complex. Lysosomes appeared to contain acid and neutral phosphatases. Cytochemistry showed that lysosomes predominate among t he unidentified vacuoles in the cytoplasm. Some vesicles are involved in the endocytic pathway, while others are derived from the Golgi comp lex. Hydrogenosomes have a rod-like or dumb-bell shape. Two of the ant erior flagella present rosettes, when observed in replicas of freeze-f ractured material, formed by circular arrangement of intramembranous p articles on both P and E faces. The other anterior and the recurrent f lagella do not show such rosettes but showed ribbon-like arrays of par ticles at the point where they emerge from the cell body.