An ultrastructural study of Dirofilaria immitis infection in the Malpighian tubules of Anopheles quadrimaculatus.
An ultrastructural study was conducted of the Malpighian tubules of Anopheles quadrimaculatus, both uninfected and following infection with Dirofilaria immitis. The Malpighian tubules in Anopheles are composed of primary and stellate cells. The primary cells are the predominant cell type and are characterized by the presence of membrane-bound, intracellular, mineralized concretions and large apical microvilli containing mitochondria. Following the infective blood meal, the microfilariae enter the primary cells of the Malpighian tubules and reside in the cytoplasm in a clear zone without a delimiting membrane. Cells in infected tubules differ from those in uninfected tubules in that the membranes of the vacuoles surrounding the concretions are disrupted in many specimens. The apical and basal cell membranes and the mitochondria associated with these are not disrupted during the first 6-8 days of infection. These observations differ sharply from those previously described in Aedes taeniorhynchus infected with D. immitis. The observations are consistent with the hypothesis that the extended transport capacity observed in previous physiological studies of An. quadrimaculatus infected with D. immitis are dependent on the prolonged normal ultrastructure of the apical microvilli, mitochondria, and basal membranes.
Bradley
T J
TJ
Department of Developmental and Cell Biology, University of California, Irvine 92717.
Nayar
J K
JK
D000818:Animals; D000852:Anopheles / Q000469:parasitology*; D002988:Cloaca / Q000648:ultrastructure*; D004183:Dirofilaria immitis / Q000648:ultrastructure*; D005260:Female; D005370:Filarioidea / Q000648:ultrastructure*; D007303:Insect Vectors / Q000469:parasitology*; D008317:Malpighian Tubules / Q000469:parasitology / Q000648:ultrastructure*; D008842:Microfilariae / Q000648:ultrastructure; D008854:Microscopy, Electron; D008871:Microvilli / Q000648:ultrastructure; D008928:Mitochondria / Q000648:ultrastructure