LIGNOT, Jean H; SECOR, Stephen M; CNRS University Louis Pasteur; University of Alabama: Apoptosis in the intestinal mucosa of the Burmese python

Burmese pythons (Python molurus) are highly adapted to infrequent feeding, up and down-regulating their gastrointestinal performance at the beginning and completion of each meal. Highlights of this response are 5 to 20-fold increases in nutrient transport rates and a doubling of small intestinal mass. To further characterize the mechanisms underlying the morphological plasticity of the pythons’ intestine, we investigated cellular apoptosis within the intestinal villi of P. molurus using light and scanning electron microscopy. Intestinal samples were taken from pythons fasted (30 d since last meal) and at 1, 2, 3, 4, 6, and 14 days postfeeding. For fasted snakes there was little sign of apoptosis occurring along the intestinal villi. Enterocytes were characteristically hypotrophic possessing very short microvilli. By 1 d postfeeding, enterocytes had doubled in size and microvilli had increased 4-fold in length. At this time we observed apoptotic cells (TUNEL-positive) accumulating largely at the villus tip. This was followed by the observed shedding of cells from the villus tip and sides at 2 to 4 d postfeeding. These events gradually attenuated by 4 to 6 days postfeeding. By 14 d postfeeding, digestion had been completed and the intestinal villi had returned to a morphological state characteristic of the fasting intestine. For the python, feeding triggers a series of cellular events (apoptosis, cell shedding, cellular proliferation) of the intestinal mucosa as it upregulates its performance and digest its meal.