  The postprandial morphological changes of the intestinal epithelium of
Burmese pythons were examined using fasting pythons and at eight time points
after feeding. In fasting pythons, tightly packed enterocytes possess very
short microvilli and are arranged in a pseudostratified fashion. Enterocyte
width increases by 23% within 24 h postfeeding, inducing significant increases
in villus length and intestinal mass. By 6 days postfeeding, enterocyte volume
had peaked, following as much as an 80% increase. Contributing to enterocyte
hypertrophy is the cellular accumulation of lipid droplets at the tips and
edges of the villi of the proximal and middle small intestine, but which were
absent in the distal small intestine. At 3 days postfeeding, conventional and
environmental scanning electron microscopy revealed cracks and lipid extrusion
along the narrow edges of the villi and at the villus tips. Transmission
electron microscopy demonstrated the rapid postprandial lengthening of
enterocyte microvilli, increasing 4.8-fold in length within 24 h, and the
maintaining of that length through digestion. Beginning at 24 h postfeeding,
spherical particles were found embedded apically within enterocytes of the
proximal and middle small intestine. These particles possessed an annular-like
construction and were stained with the calcium-stain Alizarine red S suggesting
that they were bone in origin. Following the completion of digestion, many of
the postprandial responses were reversed, as observed by the atrophy of
enterocytes, the shortening of villi, and the retraction of the microvilli.
Further exploration of the python intestine will reveal the underlying
mechanisms of these trophic responses and the origin and fate of the engulfed
particles.
