Figure 1. Preparations used to study effects of stretch on mechanoreceptor activity.

A, the preparation was pinned along one edge, serosa uppermost, and connected via a metal rake on the other edge to a microprocessor-controlled stepper motor. Changes in length of the preparation were imposed and the tension developed by the tissue was recorded via the isometric force transducer. B, the preparation was similarly pinned down one edge, but the rake on the other edge was attached to a thread that ran, via a pulley, to an isotonic length transducer. Stretch was applied by increasing the counterweight on the transducer while recording the resulting changes in length of the preparation, which was free to shorten. By aligning the preparation appropriately, it was possible to stimulate and record from longitudinal and/or circular muscle with either preparation.