Endometrium of cavitary rudimentary horns in unicornuate uteri.

The rudimentary horns removed from ten patients with unicornuate uterus, subclass A1b, were studied by light and scanning electron microscopy. Seven of the horns removed were small in volume and three were larger. In six of the seven rudimentary horns without hematometra, the endometrial mucosa did not correspond to the cycle phase of the endometrium of the hemiuterus. We consider that the absence of cyclic changes in the endometria of the smaller horns may be attributed to reduced vascular supply, to the absence of any isthmocervical structure, and to the qualitative and/or quantitative differences in endometrial mucosal receptors