This illustration shows a cross section of a man’s testicle, or testis, which is a rounded organ, located under the penis in a sac-like pouch. At the top of each testis is the epididymis, a tightly coiled tube. The head of the epididymis connects to the testis through a series of ducts, ductuli efferentes, ending at the mediastinum. The tail of the epididymis connects to the ductus deferens. The spermatic cord surrounds the epididymis and ductus deferens and the blood vessels that nourish the testis. Copyright 2004 American Society of Clinical Oncology. Robert Morreale/Visual Explanations, LLC.