Studies on the Uterine Movement by Means of the Double Balloon Technique Part 1 Double Balloon Technique for Recording Uterine Movement of Conscious Rabbits in the Chronic Experiment, and Some Observations on the Physiology of Uterine Movement

In order to record the uterine movement of a rabbit over a long period of time, under as physiological a condition as possible and by a simple procedure and to observe the mode of propagation of uterine contraction from such a record, a method of detaining double balloons in the uterus was devised. The balloons were made of raw rubber, the centers of two balloons being apart at a distance of 3 cm and were withheld inside the uterine cavity, near the Fallopian tube. Changes in the water pressure inside the balloons produced by the myometrial activity were recorded kymographically under conscious state on desired occations. Of the 57 rabbits submitted to this operation, 24 remained unharmed and were able to be used for the experiments over 6 weeks. Majority of the casualties could have been prevented by taking a little more precaution. The uterine movement curve was recorded best when the water pressure inside the balloon was 25 cm. The shape of the curves was variable, and could be classified by wave height, frequency of the waves, wave form, and rhythm. Comparatively rhythmical curves would enable prediction of the direction of peristatic movement from the time deviation of contraction waves transmitted by the two balloons. The height of uterine movement curves of rabbits varied from day to day but its maximum was found to come in intervals of 13-26 days in five rabbits. In the does known to be in heat from copulating tendencies, the wave height was generally great or there were some grouping of contraction waves. On the contrary, the waye height was small in those not in heat. It may be considered, therefore, that the periodicity in wave height described above indicates the oestrus cycle. The wave height lessened somewhat three hours after the copulation, became extremely slight 48 hours later, and the uterine movement practically stopped for over 14 days until the start of the next movement. However, frequency of uterine contraction rather increased during 12 hours following the copulation. The mode of propagation of uterine contraction as judged by the time deviation in the contraction of the two balloons was generally complicated and the march of the movement in only one direction over a long period was a rare occurrence. It may be said, however, that the direction of the wave march is generally definite when the wave height was great and in the majority of such cases this is from the tubal side to the vaginal