Postprandial morphological response of the intestinal epithelium of the Burmese python (Python molurus)

摘要

The postprandial morphological changes of the intestinal epithelium ofBurmese pythons were examined using fasting pythons and at eight time pointsafter feeding. In fasting pythons, tightly packed enterocytes possess veryshort microvilli and are arranged in a pseudostratified fashion. Enterocytewidth increases by 23% within 24 h postfeeding, inducing significant increasesin villus length and intestinal mass. By 6 days postfeeding, enterocyte volumehad peaked, following as much as an 80% increase. Contributing to enterocytehypertrophy is the cellular accumulation of lipid droplets at the tips andedges of the villi of the proximal and middle small intestine, but which wereabsent in the distal small intestine. At 3 days postfeeding, conventional andenvironmental scanning electron microscopy revealed cracks and lipid extrusionalong the narrow edges of the villi and at the villus tips. Transmissionelectron microscopy demonstrated the rapid postprandial lengthening ofenterocyte microvilli, increasing 4.8-fold in length within 24 h, and themaintaining of that length through digestion. Beginning at 24 h postfeeding,spherical particles were found embedded apically within enterocytes of theproximal and middle small intestine. These particles possessed an annular-likeconstruction and were stained with the calcium-stain Alizarine red S suggestingthat they were bone in origin. Following the completion of digestion, many ofthe postprandial responses were reversed, as observed by the atrophy ofenterocytes, the shortening of villi, and the retraction of the microvilli.Further exploration of the python intestine will reveal the underlyingmechanisms of these trophic responses and the origin and fate of the engulfedparticles.