Some men have a blockage which prevents the sperm from being ejaculated. For these individuals, sperm can be obtained by introducing a needle into the testicle (where sperm are produced) or the epididymis (where sperm are stored) while under anesthesia. Tissue containing sperm is aspirated into the needle and then dissected in the laboratory to obtain the sperm. Since the motility of these sperm is poor, intracytoplasmic sperm injection is required to insure fertilization.