The testicles are a pair of organs located in the scrotum. Together with the adjacent epididymides, they are part of the internal reproductive organs.
The testicles have the function of producing male sex hormones (secretion of testosterone) and sperm cells (sperm). The testicle is covered by a tough layer of connective tissue (tunica albuginea). The inside contains small testicular lobules/seminiferous tubules with efferent ducts that connect the rete testis to the epididymis. The seminiferous tubules consist of germinal epithelium that produces precursors of sperm.
The Leydig cells, located between the seminiferous tubules, produce the male sex hormone testosterone. Upon reaching puberty, several million sperm cells are produced per day. These need about two months to mature under the influence of hormones. The sperm cells are stored in the epididymis and are then transported through the vas deferens (ductus deferens) to the seminal vesicles and the prostate. During orgasm, the sperm cells are ejected through the urethra along with a nourishing seminal fluid.