Passage pressure across the uterotubal junction during the 4 phases of the oestrous cycle in the rat

Abstract

The closure strength of the uterotubal junction (UTJ) was measured in 90 2.5 month old cycling female Wistar rats, assigned to 9 groups of 10 each. The passage pressure in both left and right UTJ were registered in pro-oestrus, oestrus, metoestrus and dioestrus phases. Five other groups were formed with rats which had been treated for 3 weeks with oestradiol (group E) or medroxiprogesterone acetate (group P), and with animals which had been ovariectomized 75 days prior to registering the pressure (ovariectomized group) or ovariectomized and treated with oestradiol (group Ov-E) or medroxiprogesterone acetate (group Ov-P). The passage pressure of the right and left UTJ in each animal was similar in each of the groups. The pressures obtained in the oestrus phase or in the E and Ov-E groups were significantly smaller than those registered in dioestrus or in the P and Ov-P groups, and only slightly smaller than that obtained in the pro-oestrus and metoestrus phases. The results indicate that the swelling of the mucosa mediated by oestrogens is not the cause of the tubal locking in the rat.