Question

You need to do a study with mice to test the hypothesis that running 3 hours on a treadmill will cause small tears in the Achilles tendon, whereas running 1 hour on a treadmill will not cause any tears in the Achilles tendon. You plan to detect small tears in the tendon using histological staining for collagens. You plan to use mechanical (tensile) testing because tendons with small tears will have lower elastic modulus than tendons without small tears. Please use drawings and explanations to describe the experimental design you would use for this study. Be sure to include the experimental replicates, biological replicates, and technical replicates that you would include for this study and explain why.

Answer 1

The experimental design to test the hypothesis involves using mice groups for 1 hour and 3 hours treadmill running, applying histological staining for collagen to detect tears, and measuring elastic modulus with tensile testing. Biological and technical replicates will be incorporated to ensure reliability and address individual variances among samples.

Step-by-step explanation:

Experimental Design for Tendon Injury Study in Mice

To test the hypothesis that running 3 hours on a treadmill will cause small tears in the Achilles tendon, while running 1 hour will not, a controlled experimental design should be implemented. This would include two groups of mice: one subjected to 3 hours of treadmill running (the experimental group) and another subjected to 1 hour of treadmill running (the control group). Both biological replicates and technical replicates should be used. Biological replicates will consist of multiple mice for each group to ensure the results are not due to individual variability. Technical replicates involve multiple measurements or observations of the same sample to confirm consistency.

Histological staining for collagens will be used to detect small tears in the tendons, providing a visual confirmation of injury. The elastic modulus of the tendons will be measured through mechanical tensile testing to assess changes in the tendon's stiffness due to potential damage. Tendons with tears are expected to have a reduced elastic modulus compared to those without tears.

The study's validity would be strengthened by including multiple mice in each group to serve as experimental replicates, which account for the biological variance among the subjects. Technical replicates such as repeating histological staining and mechanical testing several times for each sample ensure the reliability of the data.

To draw a conclusion from the results, we would compare the presence and extent of tendon damage between the two groups. If a significant difference is found, where the 3-hour group shows more tears and reduced elasticity, the hypothesis would be supported. These findings can have implications for understanding stress-related tendon injuries across various activities that may lead to conditions such as tendinitis.