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3. Take the Quiz: The Human Body

Medical Author:

Stephen W Leslie, MD, FACS

Medical Editor:

William C. Shiel Jr., MD, FACP, FACR

William C. Shiel Jr., MD, FACP, FACR

Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.

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The testes (or testicles) are two olive-sized oval bodies, one on the right side and one on the left side. The testes have two main functions:

• to produce sperm (the male sex cell), and
• to produce testosterone (the male sex hormone).

The epididymides and the vasa deferentia are attached to the testicles and are important in transporting sperm cells after they develop in the testes.

The term testicles includes the testes as well as the surrounding structures, such as the vas deferens and the epididymis. These two names, testes and testicles, are often used interchangeably even though their definitions are slightly different.