Where does sperm travel to attach to the wall of the placenta?

Sperm does not travel to the placenta; rather, it fertilizes an egg in the fallopian tube. Once fertilization occurs, the resulting zygote travels to the uterus, where it implants itself into the uterine lining, not the placenta. The placenta develops later as the embryo grows, facilitating nutrient and waste exchange between the mother and the developing fetus.