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“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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“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

background and hypothesis
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
  • 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
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
results and discussion
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
relative body mass
Relative Body Mass
  • Group A lost an average of 82% of body mass
  • B gained 30%
  • C only gained a small amount
relative small intestine and liver mass
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
organ size changes small intestine
Organ Size ChangesSmall Intestine
  • 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

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
relative liver mass
Relative Liver Mass
  • Group A declined by 90%
  • Group B showed a plateau and then increased
  • Group C peaked 3-5 days after feeding.
  • 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
How did histological samples/techniquesimprove the article?Why is this article important? Would you have done it differently?