As we all know, the penis is a cylindrical, flexible and pendant organ, which become larger and harder when the male is sexually excited. This unique ability enables the male to sexually couple with the female and transfer semen to the vagina.
The penis is made of three columns of erectable tissue that are wrapped in connective tissue and covered with skin. Also, the penis can be divided into three parts that are called the root, the body (or shaft) and the glans penis. The root attachés the penis to the pubic arch, and the body is visible pendent portion. Out of the said three columns of tissue, the middle column that surrounds the urethra (the urine/semen tube) expands at the end to form the glans penis. The urine tube opens at the tip of the glans penis, and this opening is called the urethral orifice. A lose fold of skin (called the foreskin or prepuce) covers the glans penis.
The testicles are a pair of oval-shaped glands, which are contained in a pouch (a bag of skin), called the scrotum. The Scrotum is divided by a membrane (a thin skin-like tissue) into two parts, each half with one testicle. The scrotum is located behind the penis, suspending from the root of the penis. This exposed location of the scrotum allows the testicles to stay a few degrees cooler than the body temperature, which is the ideal temperature for sperm production. The testicles produce the whitish sperm-bearing fluid along with male sex hormones. Sperm are the male reproductive cells that are able to fertilize female egg cells (ovum). Several hundred million sperm are produce in the testicles each day. These sperm travel to a small tube called the epididymis situated on the outer surface of the testicle and stay there.
During sexual intercourse, the sperm move out of the epididymis and travel through a tube called vas deferens (or called ductus deference). This tube passes up from the epididymis towards the bladder, and just beneath the bladder it joint with a duct from the seminal vesicle and passes through the prostate gland produces a milky fluid and the seminal vesicle adds nutrients such as fructose, vitamin C, and various amino acids. The seminal fluid is the added to the sperm travelling in the vas deferens making semen.
So, semen is the medium in which sperm leave the body. Semen provides a water-like environment for the sperm to swim in and also nutrients and protection for the sperm cells. The urethra is the duct in which both urine and semen travel out of the penis. But these two flood fluids do not mix because the prostrate gland closes the bladder during intercourse. Finally, semen is forced out of the penis in short and rapid muscles spasms, accompanied with an orgasm by the male. An average healthy male ejaculates about three to five milliliters of semen, each ml containing around hundred million sperm.