LIGNOT, J H; SECOR, S M; University Louis Pasteur / CNRS-Strasbourg ; University of Alabama: Postprandial morphological changes of the intestinal villi and enterocytes in the Burmese python

As an apparent adaptive response to feeding infrequently on large meals, Burmese pythons (Python molurus) experience large regulatory swings in GI function and morphology with the start and completion of each meal. Characteristic of this response is a 2-fold increase in the mass of the intestinal mucosa within several days after feeding and a subsequent regression of the mucosa once digestion has finished. Unknown are the regulatory mechanisms and cellular dynamics that underlie the morphological flexibility of the pythons’ intestinal mucosa. In this study we employed light and electron microscopy (SEM and TEM) techniques to examine the postprandial morphological changes of the intestinal villi and enterocytes of P. molurus. Samples examined were taken from fasted pythons (30 d since last meal) and pythons sacrificed at 1, 2, 3, 4, 6, and 14 days postfeeding. Within 1 d postfeeding, intestinal microvilli had increased in length by several-fold as the enterocytes experienced hypertrophy. Beginning at 2 d postfeeding, some of the enterocytes were missing microvilli and experiencing apoptosis. Deep cracks connecting shedding cells appeared longitudinally and were clearly visible along the sides and mostly on top of the villi. These events peaked 3 days after feeding and attenuated gradually 4 and 6 day after ingestion. By 14 d postfeeding, enterocytes had returned to a hypotrophic state characteristic of the fasting intestine. Python enterocytes therefore experience rapid hypertrophy soon after feeding concurrent with the observed increase in their transport of nutrients. The shedding of enterocytes several days into digestion is suggestive of a matched increase in rates of enterocyte