Fig. 8.

The anal canal was harvested without and with probes of increasing diameter (4.5, 6, 9 mm) and immersion fixed in phosphate-buffered formalin. EAS muscle fibers were dissected, fixed on microscopic slides, and subjected to laser diffraction. A: stretch-dependent increase in EAS sarcomere length (n = 4–6 for each probe size). B: regional evaluation of sarcomere length at 12, 3, 6, and 9 o'clock positions around the circumference of the anal canal (n = 4–6 for each probe size). *Statistically significant increase (P < 0.05).