The testes consist of two oval-shaped glands about 1 1/2 inches long and 1 inch wide. The testes are suspended in a sac called the scrotum outside the body to maintain the lower temperature necessary for efficient sperm production. Each of the testes consists of several sections (lobules), and each lobule consists of a narrow, but long, coiled seminiferous tubule.
From the age of puberty, the cells of the seminiferous tubules are almost continuously producing spermatozoa (sperm), the male reproductive cells. Other cells, referred to as interstitial cells, secrete the male hormone testosterone into the blood. These cells are located in numerous clusters in the connective tissue between the seminiferous tubules. Testosterone performs several functions: it is important to the development of masculine characteristics, it promotes and maintains the development of the male accessory organs (the prostate gland, seminal vesicles, etc.), and it has a stimulating effect on protein anabolism.