Testes Overview

The testes (or testicles) are a pair of sperm-producing organs that maintain the health of the male reproductive system. The testes, like their female counterpart the ovaries, are known as the gonads. Their primary functions are reproductive organs.

In addition to their role in the male reproductive system, the testes also have the distinction of being an endocrine gland because they secrete testosterone – a hormone that is vital to the normal development of male physical characteristics. The testes are twin oval-shaped organs (about the size of a large grape) and are located within the scrotum, which is the loose pouch of skin that hangs outside the body behind the penis. The testosterone is necessary for physical development and also maintains libido (sexual desire or sexual energy), maintains fertility, muscle strength and bone density.

The hypothalamus and the pituitary gland control how much testosterone the testes produce and secrete. The hypothalamus sends a signal to the pituitary gland to release pituitary hormones (follicle stimulating hormone and luteinizing hormone). Luteinizing hormone (LH) stimulates testosterone production. If too much testosterone is produced, the hypothalamus alerts the pituitary gland to make less LH, which tells the testes to decrease testosterone levels. Follicle stimulating hormone (FSH) is the hormone that promotes normal sperm production.

Disorders of the Testes

Hypogonadism is a testicular disorder associated with low testosterone. Having testosterone levels that are too low causes a variety of problems, including:
• Decreased sex drive (lack of libido) and decrease in sexual function ( lack of erection strength; frequency)
• Diminished muscle mass
• Low sperm count (reduced fertility)
• Loss of body hair
• Feeling poorly/fatigue

There are two types of Hypogonadism – primary and secondary. Primary refers to a defect with the testicles, and secondary involves a problem in the pituitary gland that indirectly affects testosterone production.

The condition may be caused by many things and is most commonly the result of:
• Aging or obesity
• Defects in the pituitary and/or hypothalamus, such as pituitary tumors (which adversely affect the pituitary’s ability to function normally) and high prolactin levels (too much of the hormone causes a drop in LH and then decreased testosterone levels)
• Medication, excess alcohol or pain medications
• Testes-based conditions, such as infections, genetic defects, tumors, severe injury and radiation or chemotherapy, can deplete testosterone levels. Another cause of testicular cell destruction can be from autoimmune antibodies against the testicle.

The testes play a vital role not only in the male reproductive system but in the endocrine system as well. The release of the hormone testosterone is integral to the healthy development of male physical characteristics.