““Structural Flexibility of the Structural Flexibility of the Small Intestine and Liver of Small Intestine and Liver of

Garter Snakes in Response to Garter Snakes in Response to Feeding and Fasting” Feeding and Fasting”

Written by: J.M. Starck and K. Written by: J.M. Starck and K. BeeseBeese

Power Point by Jason GeorgePower Point by Jason George

Background and HypothesisBackground and Hypothesis

Garter Snake Garter Snake Thanmophis sirtalis Thanmophis sirtalis parietalisparietalis

The experiment is to determine the effect The experiment is to determine the effect of diet changes on the morphology of the of diet changes on the morphology of the small intestine and liver of the garter small intestine and liver of the garter snakesnake

The Burmese python was used as a The Burmese python was used as a template template

MethodMethod

12 snakes12 snakes Before experiment, fed every third Before experiment, fed every third

dayday Kept under same conditionsKept under same conditions Split into 3 groups of four snakes Split into 3 groups of four snakes Feeding trial lasted 4 weeksFeeding trial lasted 4 weeks Meal size ≈12% of snake body massMeal size ≈12% of snake body mass Diet of earthworms and/or sliced Diet of earthworms and/or sliced

fishfish

Group A fasted entire 4 weeksGroup A fasted entire 4 weeks Group B was fed every other dayGroup B was fed every other day Group C was fed once a weekGroup C was fed once a week Group A was killed after 4 weeks of Group A was killed after 4 weeks of

fastingfasting Group B was killed 2 days after last Group B was killed 2 days after last

feedingfeeding Group C was killed 1 week after last Group C was killed 1 week after last

feedingfeeding Techniques used: Ultrasonography, Techniques used: Ultrasonography,

Histology, Light microscopy, and Histology, Light microscopy, and Transmission electron microscopyTransmission electron microscopy

Results and DiscussionResults and Discussion

Measurements of body mass are Measurements of body mass are expressed relative to the mass of expressed relative to the mass of each snake on the day before the each snake on the day before the experiment startedexperiment started

Data aberrations from individual Data aberrations from individual snakes were due possibly from snakes were due possibly from moltingmolting

In groups B and C body mass In groups B and C body mass includes ingested foodincludes ingested food

Relative Body MassRelative Body Mass

Group A lost Group A lost an average an average of 82% of of 82% of body massbody mass

B gained B gained 30%30%

C only C only gained a gained a small small amountamount

Relative Small Intestine and Relative Small Intestine and Liver MassLiver Mass

Group A Group A 3.11±0.22%3.11±0.22% after after 4 weeks of fasting4 weeks of fasting

Group B Group B 5.04±1.13% 2 5.04±1.13% 2 days after feedingdays after feeding

Group C Group C 4.27±1.01% 7 4.27±1.01% 7 days after feeding days after feeding

Group A Group A 2.5±0.6% after 4 2.5±0.6% after 4 weeks of fastingweeks of fasting

Group B Group B 4.1±0.2% 2 days 4.1±0.2% 2 days after feedingafter feeding

Group C Group C 3.3±0.4% 7 days 3.3±0.4% 7 days after feedingafter feeding

Organ Size ChangesOrgan Size ChangesSmall IntestineSmall Intestine

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

Length of Intestinal Villi and Length of Intestinal Villi and MicrovilliMicrovilli

A 0.6±0.2mmA 0.6±0.2mm B 1.2±0.2mmB 1.2±0.2mm C 0.9±0.3mmC 0.9±0.3mm

Fasting Fasting Snakes Snakes 2.4±0.6µm2.4±0.6µm

Digesting Digesting Snakes Snakes 3.4±0.6µm3.4±0.6µm

Relative Liver MassRelative Liver Mass Group A declined by 90%Group A declined by 90% Group B showed a plateau and then Group B showed a plateau and then

increasedincreased Group C peaked 3-5 days after feeding.Group C peaked 3-5 days after feeding.

HistologyHistology The garter snake was just like the The garter snake was just like the

Burmese pythonBurmese python Small intestine was lined by Small intestine was lined by

transitional epitheliumtransitional epithelium Lipid droplets filled enterocytes Lipid droplets filled enterocytes

and hepatocytes in response to and hepatocytes in response to digestiondigestion

Cell proliferation occurred while Cell proliferation occurred while organ decreased to replace cells organ decreased to replace cells used in digestionused in digestion

How did histological How did histological samples/techniquessamples/techniquesimprove the article?improve the article?

Why is this article important? Why is this article important? Would you have done it Would you have done it differently?differently?