An ultrastructural, cytochemical and freeze-fracture study of the surface structures of Brugia malayi microfilariae.
Ultrastructural analysis of the cuticle of Brugia malayi microfilariae indicated that it is composed of 2 regions: the inner one 15-20 nm thick with a homogeneous aspect and the outer one, designated as epicuticle, which is 15-20 nm thick. Three laminae separated by electron-lucent regions were seen in the epicuticle. Labeling of the cuticle and epicuticle of B. malayi and Wuchereria bancrofti microfilariae was observed when thin sections of Lowicryl-embedded parasites were incubated in the presence of gold-labeled phospholipase-C. Replicas of freeze-fractured microfilariae showed the presence of 2 fracture planes in the epicuticle and no fracture plane in the inner region of the cuticle. The P face of the epicuticle outer fracture plane presented few particles similar to intramembranous particles (IMPs). The epicuticle inner fracture plane P and E faces presented large numbers of densely-packed small particles and many protuberances. Also, fracture faces of hypodermal and muscle cell plasma membranes were analyzed. Faces P and E of fractured membranes showed the presence of typical IMPs. P faces of both membranes showed larger amounts of particles than E faces. Fracture of muscle plasma membrane revealed a linear array of particles disposed in parallel rows on its P face.
Araujo
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Laboratório de Ultraestrutura Celular Hertha Meyer, Instituto de Biofisica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Brazil.
Souto-Padrón
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De Souza
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D000818:Animals; D002009:Brugia / Q000302:isolation & purification / Q000648:ultrastructure*; D017178:Brugia malayi / Q000302:isolation & purification / Q000648:ultrastructure*; D002462:Cell Membrane / Q000648:ultrastructure; D005614:Freeze Fracturing; D005849:Gerbillinae / Q000469:parasitology; D008854:Microscopy, Electron; D014958:Wuchereria bancrofti / Q000648:ultrastructure