“Structural Flexibility of the Small Intestine and Liver of Garter Snakes in Response to Feeding and Fasting” Written by: J.M. Starck and K. Beese Power Point by Jason George

Background and Hypothesis Garter Snake Thanmophis sirtalis parietalis Garter Snake Thanmophis sirtalis parietalis The experiment is to determine the effect of diet changes on the morphology of the small intestine and liver of the garter snake The experiment is to determine the effect of diet changes on the morphology of the small intestine and liver of the garter snake The Burmese python was used as a template The Burmese python was used as a template

Method 12 snakes 12 snakes Before experiment, fed every third day Before experiment, fed every third day Kept under same conditions Kept under same conditions Split into 3 groups of four snakes Split into 3 groups of four snakes Feeding trial lasted 4 weeks Feeding trial lasted 4 weeks Meal size ≈12% of snake body mass Meal size ≈12% of snake body mass Diet of earthworms and/or sliced fish Diet of earthworms and/or sliced fish

Group A fasted entire 4 weeks Group A fasted entire 4 weeks Group B was fed every other day Group B was fed every other day Group C was fed once a week Group C was fed once a week Group A was killed after 4 weeks of fasting Group A was killed after 4 weeks of fasting Group B was killed 2 days after last feeding Group B was killed 2 days after last feeding Group C was killed 1 week after last feeding Group C was killed 1 week after last feeding Techniques used: Ultrasonography, Histology, Light microscopy, and Transmission electron microscopy Techniques used: Ultrasonography, Histology, Light microscopy, and Transmission electron microscopy

Results and Discussion Measurements of body mass are expressed relative to the mass of each snake on the day before the experiment started Measurements of body mass are expressed relative to the mass of each snake on the day before the experiment started Data aberrations from individual snakes were due possibly from molting Data aberrations from individual snakes were due possibly from molting In groups B and C body mass includes ingested food In groups B and C body mass includes ingested food

Relative Body Mass Group A lost an average of 82% of body mass Group A lost an average of 82% of body mass B gained 30% B gained 30% C only gained a small amount C only gained a small amount

Relative Small Intestine and Liver Mass Group A 3.11±0.22% after 4 weeks of fasting Group A 3.11±0.22% after 4 weeks of fasting Group B 5.04±1.13% 2 days after feeding Group B 5.04±1.13% 2 days after feeding Group C 4.27±1.01% 7 days after feeding Group C 4.27±1.01% 7 days after feeding Group A 2.5±0.6% after 4 weeks of fasting Group B 4.1±0.2% 2 days after feeding Group C 3.3±0.4% 7 days after feeding

Organ Size Changes Small Intestine Mucosa decreased to 80% in Group A and increased in Groups B and C to 150% and 120% Mucosa decreased to 80% in Group A and increased in Groups B and C to 150% and 120%

Length of Intestinal Villi and Microvilli A 0.6±0.2mm A 0.6±0.2mm B 1.2±0.2mm B 1.2±0.2mm C 0.9±0.3mm C 0.9±0.3mm Fasting Snakes 2.4±0.6µm Digesting Snakes 3.4±0.6µm

Relative Liver Mass Group A declined by 90% Group A declined by 90% Group B showed a plateau and then increased Group B showed a plateau and then increased Group C peaked 3-5 days after feeding. Group C peaked 3-5 days after feeding.

Histology The garter snake was just like the Burmese python The garter snake was just like the Burmese python Small intestine was lined by transitional epithelium Small intestine was lined by transitional epithelium Lipid droplets filled enterocytes and hepatocytes in response to digestion Lipid droplets filled enterocytes and hepatocytes in response to digestion Cell proliferation occurred while organ decreased to replace cells used in digestion Cell proliferation occurred while organ decreased to replace cells used in digestion

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