. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. NUTRITION IN PARANEMERTES PEREGRINA 95 Both cell types are secretory when fully developed. The basophils extrude their contents to the foregut lumen between their distal cilia, but the acidophils open either directly to the lumen or discharge their spheres via secretory tracts extending between the columnar cells. Shortly after ingestion is commenced, evidence of secretion can be found in the foregut lumen, the basophilic component appearing as finely participate and irregular "strings," the acidophilic spheres com
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. NUTRITION IN PARANEMERTES PEREGRINA 95 Both cell types are secretory when fully developed. The basophils extrude their contents to the foregut lumen between their distal cilia, but the acidophils open either directly to the lumen or discharge their spheres via secretory tracts extending between the columnar cells. Shortly after ingestion is commenced, evidence of secretion can be found in the foregut lumen, the basophilic component appearing as finely participate and irregular "strings," the acidophilic spheres complete and isolated. There is some evidence to suggest that the acidophilic secretions initially expand after discharge, and then rupture to release their contents into the FIGURE 1. Parancmcrtes peregrina. Stereogrammatic representation to show the relative positions of the proboscis and alimentary canal, characteristic of this type of hoplonemertean. The appearance of the body in transverse section is shown for two points in the lower diagrams; , cecal diverticulum; , cerebral ganglion; f., foregut; i., intestine; , intestinal cecum; p., proboscis; r., rhynchocoel; rd., rhynchodeum; , rhynchodeal pore. The distribution of the adipophilic glands in the foregut is such that they are concentrated in the anterior half where they and the columnar cells occur in approximately equal numbers. A short region immediately adjoining the rhynchodeum tends to lack these glands, however, and it is probable that this portion of the foregut is equivalent in the esophagus described for other hoplo- nemertean species. The posterior foregut epithelium shows a progressive decrease in the density of the acidophils as the intestine is approached, and in the region just anterior to the hindgut the ratio of gland to columnar cells is 1:20 or more. A distinct pyloric tube is absent from Paranemertes and there is no decrease in epithelial height although the foregut tends to
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
