Study of the vasculature of the caprine reproductive organs using the tissue-clearing technique, with special reference to the angioarchitecture of the utero-ovarian vessels and the adaptation of the ovarian and/or vaginal arteries to multiple pregnancies.

Arteries of the reproductive tracts of nonpregnant does and does at 4, 7, 10, 13, 16, and 18 weeks of gestation were injected in situ with Microfil. The tracts were fixed, dehydrated, and rendered transparent to reveal the paths of arteries. The tortuous ovarian artery lay in close apposition to the uterine tributary of the ovarian vein, an arrangement that may serve as a local utero-ovarian pathway for the corpus luteum (CL) luteolysis at the end of nonfertile estrous cycle. During pregnancy, this arteriovenous arrangement might transfer luteotropic substances from uterus to ovary, which might serve in maternal recognition of pregnancy and fit the fact that the goat is CL-dependent throughout gestation. In some cases of triplets, the size of the uterine branch of the ovarian artery was equal to or even larger than that of its parent artery and/or the ipsilateral uterine artery, and the vaginal artery contributed a connecting branch to the uterine artery. These physiological adaptations of the ovarian and/or vaginal arteries, which have not previously been described, correlate well with the increasing nutrient demands of the growing multiple fetuses.