Scanning electron microscopy of the duodenal mucosa of lambs infected with Trichostrongylus colubriformis

Duodenal mucosae of uninfected lambs and lambs inoculated at least 16 days earlier with 85000–140000 Trichostrongylus colubriformis larvae were examined with the scanning electron microscope. Normal duodenum had tall spatulate villi with surface folds upon which goblet cells and a regular pattern of hexagonal enterocytes were seen. Micro villi on normal enterocytes were closely packed and imparted a granular surface texture. In heavily infected areas of gut the villi were atrophic, the mucosa sometimes being composed of irregular masses and ridges, with crypt mouths, often surrounded by collars of cells, opening into the surface. More severely affected mucosae were flat, with protuberant collars of cells surrounding crypt mouths. There were rounded bodies, interpreted as sloughing enterocytes, or inflammatory cells, on the mucosal surface. Apices of enterocytes were domed and microvilli were sparse and irregular. Micro-organisms were numerous on cell surfaces. Nematodes were located in sinuous thin-walled tunnels in the epithelium. The mucosal microtopography is compared with that of coeliac disease of humans, nippostrongylosis in rats and with villus atrophy in pigs.

The penetration of oncospheres of Taenia pisiformis into the intestine of the rabbit

Hatched activated oncospheres of Taenia pisiformis penetrated the intestine and attained the liver within 40 min of their inoculation into the duodenum of the rabbit. Most oncospheres in histological sections were in the epithelium, but a few were noted in the lamina propria. It is suggested that oncospheres penetrate between epithelial cells and enter subepithelial capillaries without migrating extensively in the lamina propria. Secretions of the oncospheral glands may act as a lubricant. Penetrating oncospheres elicited no tissue reaction.

Case report. Thelazia lacrymalis from the eyes of an Ontario horse

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