The uterus has an enormous capacity to enlarge during pregnancy and after calving will return to it's normal size in a process called involution. The uterine wall is fragile and contains 80 to 120 caruncles which are places where the membranes of the developing calf attaches. The uterine horn narrow to form the oviduct. The junction between the uterus and oviduct serves as a valve which is tightly shut except for short times to allow the sperm and ovum to pass. There is no direct attachment between the oviduct and ovary.
Fertilization occurs in the upper half of the oviduct.
Infundibulum - the other end of the oviduct, adjacent to the ovary, and shaped like a funnel. The infundibulum partially surrounds the ovary and serves as the entrance to the oviduct and is continuous with the peritoneal cavity where the intestines are located. Their primary function is to produce ova for perpetuation of the species. In addition, the ovaries produce hormones that are indispensable in preparing the reproductive tract for pregnancy and maintaining and delivering the products of the pregnancy. This usually occurs approximately 10 to 12 hours after the end of standing heat.