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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
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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

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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

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• 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

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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

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Relative Body Mass

• Group A lost an average of 82 of body mass
• B gained 30
• C only gained a small amount

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Relative Small Intestine and Liver Mass

• Group A 3.110.22 after 4 weeks of fasting
• Group B 5.041.13 2 days after feeding
• Group C 4.271.01 7 days after feeding

• Group A 2.50.6 after 4 weeks of fasting
• Group B 4.10.2 2 days after feeding
• Group C 3.30.4 7 days after feeding

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Organ Size ChangesSmall Intestine

• Mucosa decreased to 80 in Group A and increased
  in Groups B and C to 150 and 120

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Length of Intestinal Villi and Microvilli

• A 0.60.2mm
• B 1.20.2mm
• C 0.90.3mm

• Fasting Snakes 2.40.6µm
• Digesting Snakes 3.40.6µm

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Relative Liver Mass

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

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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

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