Spontaneous contractions of the reproductive tract in laying and nonlaying hens.

The amplitude and frequency of contraction of muscle strips from the uterus, isthmus, and magnum from both laying and nonlaying hens were measured in vitro. The muscle strips from laying hens exhibited a greater amplitude of contraction (P less than .05) than the nonlayer; frequency was not significantly different between the two groups. In a comparison of organ sections tested, significant differences in amplitude, but not frequency of contraction were found. In the laying hen the magnum had the highest amplitude of contraction (2.59 mm.) followed by the uterus (1.63 mm.), and isthmus (.81 mm.).