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Structure and function of the intestinal-cloacal junction of the nematode Heterakis gallinarum
Published online by Cambridge University Press: 06 April 2009
Extract
The ultrastructure of the intestinal-cloacal junction of the male nematode Heterakis gallinarum is described. A sphincter muscle seals the lumen of the alimentary tract at this point by squeezing on the posterior cells of the intestine. These posterior cells of the intestine are unusual in that they contain numerous microtubules, and are very different from the other cells of the intestine. Electron-dense granules lie at the base of these cells where they abut on to the portion of the sphincter muscle which contains the myofilaments. It is suggested that a build-up of pressure in the intestinal lumen, brought about by the pumping action of the pharynx and/or contraction of the muscle network around the intestine, is the most probable means of opening the sphincter at defecation. On the other hand, the structure of the posterior cells of the intestine suggests that they may act as a stretch receptor which communicates with the sphincter muscle by means of a pharmacologically active substance held in the electron-dense granules which lie in the basal region of these cells.
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- Copyright © Cambridge University Press 1975
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