Angiopathies in the equine endometrial biopsy - a marker for extrauterine vascular lesions?

Endometrial, myometrial and extrauterine vessels of 13 juvenile mares, 53 adult non-pregnant mares, 11 adult pregnant mares (two of which had a rupture of the uterine artery), and 4 post-parturient mares were investigated by means of histology and immunohistochemistry. The vessels of juvenile mares did not show any alterations. The endometrial vessels of the adult non-pregnant mares, on the other hand, were characterized by mild to moderate panelastofibrosis or panfibroelastosis. The myometrial vessels revealed lesions of the same quality, but to a higher degree in one third of the mares. In the extrauterine vessels (arteria and vena uterina, ramus cranialis of the arteria and vena uterina, arteria and vena ovarica of each side) mild to moderate fibrosis and fibroelastosis of the vascular wall predominated. There was a distinct correlation between the degree of arteriosis in the uterine (endometrial and myometrial) and the extrauterine vessels. Based on these findings, the endometrial biopsy is a reliable indicator for extrauterine arterial alterations. The vascular lesions of the pregnant mares in the first half of the pregnancy resembled those of the adult non-pregnant mares. By contrast, the endometrial, myometrial and extrauterine arteries of mares in the second half of pregnancy and post-parturient mares were characterized by a pronounced hypertrophy of the myocytes within the media.