“Structural Flexibility of the Small Intestine and Liver of Garter Snakes in Response to Feeding a...
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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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Background and Hypothesis

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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. 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


Method

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


Background and hypothesis

  • 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.


Histology

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


Background and hypothesis

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


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