Final answer:
The narrowed region at the proximal end of the uterine tube, where it connects to the uterus, is called the isthmus.
Step-by-step explanation:
The proximal end of the uterine tube becomes narrowed in a region known as the isthmus. This narrowed region is critical because it is where the uterine tube connects to the uterus. Besides the isthmus, there are other parts to the uterine tube such as the ampulla, where fertilization commonly occurs, and the infundibulum, which flares out and has finger-like projections called fimbriae. The uterine tube facilitates the movement of oocytes from the ovary to the uterus, with its inner mucosa lining containing ciliated cells that guide the oocyte in the right direction.