Flexi Says: In humans, sperm are released from the body of males during ejaculation. Ejaculation occurs when muscle contractions propel sperm from the epididymes. The sperm are forced through the ducts and out of the body through the urethra. As sperm travel through the ducts, they mix with fluids from the glands to form semen. The vagina is a tube-like structure in females that receives sperm. Sperm are deposited in the vagina during sexual intercourse. They propel themselves through the uterus and enter a fallopian tube. This is where fertilization usually takes place.