The Male Reproductive System

 
The reproductive anatomy of the male is mainly external, except for the seminal vesicle.

The Penis

The penis is the erectile organ responsible for passing semen into the female's vagina. The anatomy of the penis is divided into two external sections, the body and the glans. Within the body of the penis is the corpus spongiosum containing the urethra, the tube that carries sperm. There are also two erection chambers known as corpora cavernosa which are supplied by arteries and responsible for maintaining an erection.

The glans penis is the top most end of the penis and is covered with a thin, sensitive skin. During circumcision, it is part of the foreskin that covers the glans which is removed.

The Seminal Vesicles

The seminal vesicle is within the body and next to the prostate. Along with the prostate gland, the vesicle works to provide a fluid environment for the sperm. Within the seminiferous tubules, 30 million sperm are produced daily and stored in the epididymis. Each individual sperm is shaped like a tadpole and about 1/20th of a millimeter in length. When mature, the sperm travel up the vas deferens into the seminal vesicle where they mix with fluids and are discharged from the penis via the urethra.

Ejaculate and Sperm Criteria

The average amount of ejaculate is about 3. 5 mL. Within each milliliter is approximately 60-150 million sperm, of which nearly 25% are abnormal. Only the remaining 75% are mobile and able to swim towards the egg.

In order to make a baby, the sperm must meet the following criteria:
1. Should be present in a sufficient volume of greater than 20 million sperm/ml.
2. Should be active and not clumped together (agglutinated). Weak sperm cannot get to an egg, much less penetrate it.
3. Should be fairly normal in shape and size with an oval shaped head. A round headed sperm may lack the enzymes necessary to break into the egg's shell.
4. Must not be unfavorably affected by antibodies of either partner.

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