Sample
Most of the experiments in physiology are performed in samples from animal models, normally pieces of rat intestine. Due to the complexity of the smooth muscle innervation, researchers normally need to decide which innervation they want to preserve. This decision is taking depending on the experiment to be performed, but usually only the postganglionic fiber of the parasympathetic nervous system is preserved (Figure 1).
Figure 1. Isolated sample for physiology experiments.