the experiments were carried out on 27 female rats of the Bufflo line. The research aimed at determining the influence of estrogen, progesterone and oxytocine on the spontaneous contraction in vitro. It was exhibited that: 1) The isolated strips of the rats’ uterus incubated in an automatic bath reveals spontaneous cyclic contractility for about 8-12 hours. 2) The application of oxytocine to the incubation chamber causes an increase in frequency (about 44.85 ± 13.42%) and in strength (about 39.5 ± 18.33%) of the spontaneous contraction activity of the uterus. 3) Earlier treating the rats with estrogen causes an increase in strength and a fall in frequency of the spontaneous contraction activity of the uterine muscles in rats as well as it increases the response to the stimulation with oxytocine. 4) Earlier treating the rats with progesterone causes an increase in strength and a fall in frequency of the spontaneous contraction activity of the uterine muscle in rats as well as it decreases the response to the stimulation with oxytocine.

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