. Biology of the laboratory mouse. Mice as laboratory animals; Mice; Animals, Laboratory; Mice. 364 BIOLOGY OF THE LABORATORY MOUSE Infection of the primary host occurs by ingesting the infected inter- mediate host. The cysticercoid which has developed in the intermediate host is Hberated in the intestine of its new host and within 18 days it has become attached to the epitheUum of the intestine and has developed into an adult worm. Control measures might profitably be directed toward eliminating any fleas which might be living as parasites on the animals and also toward keep- ing the feed roo
. Biology of the laboratory mouse. Mice as laboratory animals; Mice; Animals, Laboratory; Mice. 364 BIOLOGY OF THE LABORATORY MOUSE Infection of the primary host occurs by ingesting the infected inter- mediate host. The cysticercoid which has developed in the intermediate host is Hberated in the intestine of its new host and within 18 days it has become attached to the epitheUum of the intestine and has developed into an adult worm. Control measures might profitably be directed toward eliminating any fleas which might be living as parasites on the animals and also toward keep- ing the feed room or bins free from meal worms, the larvae of the Tenebrio beetle. Hymenolepis microstoma (dujardin, 1845).—This species of mouse and rat tapeworm (Fig. 143C) probably occurs much more rarely than the other two species of Hymenolepis that have been described, but it is an interesting form in that the adult is not limited to the intestine. The adults live in the duodenum and the common bile duct which, as described by Joyeux and Kobozieff (24), in intense infestation may be distended until it is as large as the duodenum. The gall bladder also may be completely filled. Joyeux and Kobozieff (24) have given a complete description of the adult worm. The measurements which they give are: length 80 mm. to 350 mm.; breadth of scolex 200 n; breadth of rostellum 100 ju; neck 600IX from base of scolex to first sign of segmenta- tion. There is a simple corona of 27 hooks. Development occurs in several insects, notably in the Tenebrio and in the rat flea, Nosopsyllus fasciatus. Dobrovolskaia-Zavadskaia and Kobozieff (10) have described lesions produced by the parasites in the liver and bile ducts. If the ductus choledocus is heavily infected, its wall becomes chronically inflamed and irregularly thickened, and the mucous membrane becomes hyperplastic. However, they state that the hyperplasia of the mucous membrane has never presented a neoplastic character. When the parasite penetrates th
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