The pathology induced in laboratory rats by metacestodes ofTaenia crassicepsandMesocestoides corti(Cestoda)

Abstract

Sprague-Dawley rats were infected by intraperitoneal injection with either the cysticerci of Taenia crassiceps or the tetrathyridia of Mesocestoides corti. Both species of metacestodes reproduce asexually in the peritoneal cavity. The effect of T. crassiceps upon the rats was to cause chronic inflammation of the peritoneum, fibrous adhesions between the visceral organs and hyperplasia of the gut mesenteries which became extended into a large sac-like structure. Dead parasites surrounded by white calcareous material were found free in the peritoneum and attached to the inner body wall and viscera. The histopathology of the hyperplastic mesenteries and fibrous membrane is described. The tetrathyridia of M. corti were found free in the peritoneal cavity as well as in the liver (mainly the left liver-lobe), gut mesenteries and in an outgrowth of the connective tissue associated with the pancreas. The connective tissue outgrowth comprised 2 layers; an inner reticular layer and a thickened marginal layer. Metacestodes were found in collagen-fibrin capsules within the connective tissue. A layer of mucopolysaccharide material was interposed between the parasite and the capsule wall. A possible method by which the parasites gain entry into the connective tissue is described. The connective tissues of rats harbouring either M. corti or T. crassiceps had increased numbers of mast cells compared to connective tissues from control rats. Younger mast cells containing biogenic amines predominated in infected tissues whereas older heparin-containing cells dominated control tissues.

Metabolic profile of the liver of mice infected with cysticerci of Taenia crassiceps

“…As betaine, in its sequential demethylation to form glycine (also elevated in the infected livers), is known to be a direct methyl-group donor in the biosynthesis of methionine, it can be postulated that these changes reflect cell growth and proliferation. This could be due to hyperplasia of the liver tissue itself or to pronounced inflammation, which has been reported for rodent hosts infected with this parasite (Freeman 1964; Chernin and McLaren 1983). Although histopathology of the liver was not examined in this study, it stance that aids in the solubilization of lipid.…”

“…the levels of hepatic glycogen and β-hydroxybutyrate remained lower and those of taurine, PC, choline, alanine and lactate were still elevated, but the concentration of glycine fell below that seen in the 84-day group and that of betaine assumed a value not statistically different from that of either the controls or the 84-day group. The concentrations of glucose, glycerophosphocholine, acylcarnitine, succinate and acetate stayed unchanged throughout the experiment.& b d y : During their existence in the mammalian host, cysticerci of Taenia crassiceps successfully resist the immunological responses of the host and induce various histopathological manifestations (Freeman 1964;Chernin and McLaren 1983;Bojail et al 1993). As they proliferate in the peritoneal cavity, their demand for nutrients increases, which results in a pronounced loss of the host's net body weight (Crompton et al 1985) and its eventual death.…”

The enigmatic eosinophil: investigation of the biological role of eosinophils in parasitic helmint infection

“…The species is of immunological interest, though, as the outcome of infection differs in rats and mice which both mount a large eosinophilia in response to the infection (Pollacco et al 1978, Chernin & McLaren 1983. In the peritoneal cavity and liver of rats the reproduction of M. corti is limited by immune responses, whereas in mice host immune responses are ineffective, so the parasites replicate unchecked and the hosts eventually die.…”

Early post-larval development of the endoparasitic platyhelminthMesocestoides corti: Trypsin provokes reversible tegumental damage leading to serum-induced cell proliferation and growth

“…corti tetrathyridia have been largely used as a cestode experimental model, especially in immunobiology, biochemistry, pharmacology, and physiology of these parasites (Chernin and McLaren, 1983;Conn and Etges, 1983;Williams and Conn, 1985;Terenina et al, 1995;Kadian et al, 1996;Cardona et al, 1999).…”