Pattern of electrical activity of the ovine uterus and cervix from mating to parturition.

The electrical activity of the uterus, greater curvature and lesser curvature, and of the cervix were recorded throughout several oestrous cycles, matings and the entire course of pregnancy in a set of ewes. In cyclic ewes, all electrode sites were active during the periovulatory period, but during the luteal phase only the cervix and lesser curvature continued to present regular activity, i.e. episodes of 6-8 min duration. Matings failed to disrupt the oestrous activity pattern in 5 out of 6 ewes. During the subsequent pregnancy in 4 ewes, activity, when present, consisted of the cyclic occurrence of regular activity episodes in the gravid horn(s) (greater curvature) and in the cervix (and lesser curvature in 1 ewe). Three phases were recognized on the basis of the activity of the greater curvature of the gravid horn(s). The first phase corresponded to quiescence of the horn from Day 5 (Day 0 = mating) to about Day 41. The second phase was marked by the sudden onset of regular activity of the uterus; frequency rapidly increased and maximal values were reached around Day 49, after which frequency progressively decreased until around Day 66. The third phase was characterized by a steady state in genital tract activity until the peripartum period. The cervix and lesser curvature activity followed an almost similar development of regular activity episodes with only slight time differences.