They are arteries and veins that branch from the uterine arteries and veins, respectively, with additional anastomoses from the ovarian arteries and veins, and penetrate and assume a circumferential course in the myometrium.
Arteries and veins originating from the uterine arteries and veins, respectively, connect to the ovarian arteries and veins. They then penetrate and follow a circumferential path through the myometrium.