Uterine Tubes

The uterine tube is divided into three main sections: the infundibulum, a funnel-shaped opening with finger-like fimbriae; the ampulla, the widest region comprising more than half the tube's length; and the isthmus, the narrowest section connecting to the uterus. Each section plays a distinct role in oocyte transport and fertilization.

During ovulation, the fimbriae extend over the ovaries and sweep their surface to capture the released oocyte. These finger-like projections cover the ovary and guide the oocyte into the infundibulum, initiating its journey through the uterine tube toward the uterus.

The ampulla is the widest section of the uterine tube and provides an optimal environment for sperm and oocyte to meet. Typically, sperm fertilizes the oocyte in the ampulla before it travels through the isthmus to the uterus, making this region ideal for successful fertilization.

Ciliated epithelial cells in the uterine tube lining generate currents in the peritoneal fluid that transport the oocyte toward the uterus. These cilia work alongside peristaltic contractions of smooth muscle layers to move the oocyte through the ampulla and toward the isthmus.

Nonciliated secretory and peg cells in the uterine tube epithelium release a nourishing fluid that sustains the oocyte during its journey. This fluid provides essential nutrients to the oocyte as it travels from the ampulla through the isthmus to the uterus.

Smooth muscle layers surrounding the mucosa contract peristaltically, complementing the work of cilia by propelling the oocyte through the uterine tube. These coordinated muscular contractions work with ciliary currents to ensure efficient transport of the oocyte toward the uterus for implantation.

After sperm fertilizes the oocyte in the ampulla, the resulting zygote travels through the isthmus, the narrowest part of the uterine tube, before reaching the uterus for implantation a few days later. This journey allows the embryo to develop while traveling to its implantation site.