Where is fertilization most likely to occur?

• A. Uterine wall
• B. Fimbria
• C. Ampulla of the Fallopian Tube
• D. Isthmus of the Fallopian Tube

Answer: (C)

Fertilization happens where the oocyte and sperm are most likely to meet in the fallopian tube, and that place is the ampulla. After ovulation, the egg is captured by the fimbriae and enters the tube, but the ampulla—the widest, distal portion of the tube—provides the environment and length needed for sperm to swim, capacitate, and bind to the zona pellucida, allowing the acrosome reaction and eventual fusion of the gametes. This region gives the best chance for fertilization to occur before the zygote begins its journey toward the uterus. The isthmus acts mainly as a conduit and gate to regulate transport, while implantation occurs later in the uterine lining, not at the site of fertilization.