Morfologia de ovos, larvas e adultos de Paratanaisia bragai (Santos, 1934) Freitas, 1959 (Digenea, Eucotylidae) e histopatologia do rim de Columba livia (Gm.) infectado

Abstract

Paratanaisia bragai is a digenetic that reaches sexual maturity in the collecting ducts of domestic and wild birds, and larval development using the snail Subulina octona or Leptinaria unilamellata. The embryonated eggs are released with the waste products of the definitive host and the infection settles in the snail by ingestion of these. After hatching, the miracidium, develop inside the snail two sporocysts generations, cercariae and metacercariae. The definitive host acquires infection by ingestion of parasitized snail. The present study was aimed to identify the action of the parasite on the kidney of pigeons, Columba livia, through histology, and the morphometry, morphology and ultrastructure using light microscopy, scanning electron and transmission of the egg, larval stages (miracidium , cercariae and metacercariae) and adult helminth P. bragai. The adults pigeons were obtained near the Central de Abastecimento do Estado do Rio de Janeiro S.A, Irajá, Município do Rio de Janeiro. After parasitological examination in the laboratory, to check infection, the pigeons infected were necropsied to collect helminth and infected kidney. The pigeons were used as uninfected controls. The experimental protocols were approved by the ethics committee on research UFRRJ. Histopathology showed dilatation of the renal tubules, with mononuclear inflammatory cells, formation of papilliform structure projecting into the tubular lumen and metaplasia of the epithelium of the collecting tubule walls, from simple cubic in the tubules uninfected to pseudostratified in infected kidney with P. bragai. The eggs are elliptical, with operculum at the anterior end and a knot at the posterior end, abopercular region. The eggshell is rough and composed of three layers: inner, middle and outer with thicknesses and different electrondense. The miracidium is elongated, with terebratorium the anterior end and body covered with cilia. The cercariae have cylindrical body that tapers slightly in the posterior region. The tegument is rough, the oral sucker is subterminal, the acetabulum stands in the middle third of the body. Papillae were observed around the oral sucker. A similar rudimentary tail structure was observed in some cercariae. The metacercariae observed through histological sections visualized the oral sucker, acetabulum, scales and cyst that consist of three layers, inner, middle and outer, of different thicknesses. The presence of the layers was confirmed by visualization of histological sections of metacercariae in scanning electron microscopy. The adult parasite is elongated and flattened body with oral sucker, pharynx, vitelline glands extending to the region of cecal bifurcation and then the median region of the body. The genital pore visualized a structure that is everted the cirrus in rosette form. In the adult stage the tegument is covered with scales of various types; simple scales, with two, three, four, five and seven divisions, a characteristic that may contribute to ratify the taxonomic classification of the parasite.