Light and electron microscopical studies of the location ofStrongyloides ratti in the mouse intestine

Abstract

This study was designed to define the precise anatomical location of Strongyloides ratti in the intestinal mucosa of the mouse. Light microscopy showed adult worms in vacuoles in close relationship with the columnar epithelium. Serial sections indicated that the adults wound their way circuitously through the mucosa, usually close to the crypts. Portions of worms were sometimes seen in the intestinal lumen. Electron microscopy demonstrated that adult worms were situated between the epithelial cells. They were never observed to penetrate the basement lamina and enter the lamina propria. Enterocytes were in close proximity to the cephalic end of worms, suggesting that the head of the moving worm forced the cells apart. More posteriorly along the worm, a fluid-filled vacuole surrounded the nematode. The surrounding epithelial cells were compressed and distorted but there was never any evidence of syncytial cell formation. The external cortical layer of worms was seen in some vacuoles, suggesting that ecdysis may occur in tunnels in the epithelium. It appears that S. ratti may create epithelial tunnels through which it moves, moults and deposits eggs. Since S. ratti is a mucosal-dwelling parasite, it is susceptible to attack by cellular elements of the host's defences.

A Role of Mast Cell Glycosaminoglycans for the Immunological Expulsion of Intestinal Nematode, Strongyloides venezuelensis

“…7). The exposure of the worms did not seem to be the result of necrosis of epithelial cells around the worms, because enterocytes around adult Strongyloides worms usually do not show signs of necrosis (29). Based on the present results, we concluded that S. venezuelensis were active in exiting and reentering the intestinal mucosa during infection and that the inhibition of reinvasion by mast cell glycosaminoglycans caused worm expulsion.…”

“…Adult Strongyloides nematodes are believed to move between intestinal cells with a continuous motion of invading and exiting the epithelial layer during infection (29). If this assumption is true, adult worms would be expelled when their reinvasion is unsuccessful.…”

Kinetics of Intestinal Lamina propria Mast Cells, Globule Leucocytes, Intraepithelial Lymphocytes, Goblet Cells and Eosinophils in Murine Strongyloidiasis

“…We have shown recently by electron microscopy that adult worms live in tunnels between the colum nar epithelial cells lining the intestinal mucosa [7], thus they are amenable to attack by various inflam matory cells. We have examined, therefore, the rela tionship between these worms and a variety of cell populations in the intestine.…”

The effect of interleukin-4 on the induction of intestinal mast cells and chronological cytokine profiles during intestinal nematode Strongyloides ratti infection

“…The second possibility involves the dierence in the site of parasitization of worms of different species. It has been reported that S. ratti adult worms localize between epithelial cells and above the basal membrane, whereby the epithelial cells are forced apart by adult worms (Dawkins et al 1983). On the other hand, it has been reported that T. spiralis fuses its body into the epithelial cell (Wright 1979).…”