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Background and Hypothesis

“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

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Background and Hypothesis

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

  2. Background and Hypothesis • 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 Burmese python was used as a template

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

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

  5. Results and Discussion • 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 • In groups B and C body mass includes ingested food

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

  7. Group A 3.11±0.22%after 4 weeks of fasting Group B 5.04±1.13% 2 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 Relative Small Intestine and Liver Mass

  8. Organ Size ChangesSmall Intestine • Mucosa decreased to 80% in Group A and increased in Groups B and C to 150% and 120%

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

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

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

  12. How did histological samples/techniquesimprove the article?Why is this article important? Would you have done it differently?

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