While women's bodies are certainly amazing machines, so are the bodies of men. Men are half of the equation when it comes to reproduction, and it is important to know just how everything functions. Unlike women with their initial egg production and maturation, sperm production is continuous, but reduces gradually with age.
A healthy and nutritious diet is extremely important in both men and women to ensure the body is functioning at its optimal peak.
The Male Organs
The reproductive organs in males include the penis, two testes or testicles, several transport and storage ducts and supporting structures. The oval-shaped testes are outside the body in a pouch of skin called the scrotum, where they maintain an optimum temperature for making sperm (approximately 3 degrees C lower than body temperature).
The testes also secrete testosterone, a male's sex hormone. From each testis, sperm pass into a "coiled tube" called the epididymis for the final stages of their maturation. They are stored there until they are either broken down and reabsorbed or ejaculated (forced by movement of seminal fluid from the accessory glands) down a duct called the vas deferens.
The two testes in the scrotum are where the sperm are manufactured in tubes called the seminiferous tubes. The sperm are stored in the epididymides, each of which is a tube about 6m (or 20 ft) long. These are tightly coiled and bunched into a length of about 4 cm or 2 inches.
Each testis is covered by a thin layer of tissue called the tunica vaginalis and a layer of connective tissue called fascia. An outer layer (called the dartos muscle) relaxes in hot weather and drops the testes to keep them cool. This same muscle draws them up in cold weather so the testes do not become overly chilled.
The spermatic cord suspends each testis within the scrotum and contains the lymph vessels, the testicular artery, nerves and the vas deferens.
If one were to draw a midline section through the lower abdomen of a male it would show how the penis and scrotum hang outside the body, but inside the body is a complex system of tubes, ducts and glands where the sperm mature and are stored before being ejaculated in the semen.
The Accessory Glands
The seminal vesicles and the prostate and bulbourethral glands together make up the accessory glands. The secretions from these glands are added to sperm during ejaculation. By volume, fluid from the seminal vesicles make up about 60 percent of the semen and contain sugar, vitamin C and prostaglandins.
Prostate secretions account for some 30 percent of the semen, and include fatty acids, salts, cholesterol and enzymes to balance the semen's acid-alkali balance. The bulbourethral gland secretions make up about 5 percent of the semen and neutralize the acidity of urine traces in the urethra.
Each testis is a mass of more than 800 tightly folded and looped seminiferous tubules. The sperm begin here as blob-like cells called spermatogonia lining the inner wall. As they mature, the sperm develop tails and move toward the middle of the tubule. Thousands of sperm are produced every second, with each sperm taking approximately two months to mature.
The Sperm's Pathway
When ejaculation occurs, waves of muscle contractions squeeze the sperm in their fluid from the epididymis along the vas deferens. This tube is joined by a duct from the seminal vesicle to form the ejaculatory duct. Within the prostate gland, the left and right ejaculatory ducts join the urethra.
In a male, the urethra is a dual-purpose tube that is tasked with carrying urine from the bladder during urination and sperm from the testes. However, during ejaculation the sphincter at athe base of the bladder is closed because of high pressure in the urethra, which prevents urine from passing through.
When a male is aroused, large quantities of arterial blood enter the corpus spongiosum and corpus cavernosum, serving to compress the veins. The result is that blood cannot drain from the penis and it becomes erect and hard.
Semen, or seminal fluid, is made up of sperm mixed with fluid added by the accessory glands, including the prostate gland. Fluid is secreted by the prostate gland through tiny ducts and mixes with sperm as they are ejaculated down the urethra. The final mix of ejaculation contains around 300 to 500 million sperm in 2-5 ml of fluid.
- Marieb, E.N. & Hoehn, K. Human Anatomy & Physiology (8 edition), Pearson Education, Inc (2004)
- McCracken, T. & Walker, R. New atlas of human anatomy, London : Constable (2001)
- Parker, S. The Concise Human Body Book, Dorling Kindersley Limited (2009)
- Winston, R. et al. Human: The Definitive Visual Guide, DK Publishing, Inc (2004)
- Ullmann, H.F. Atlas of Anatomy, Elsevier GmbH, Munich (2009)
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While the most common cause of infertility is due to the woman's ovulation, male infertility can also be a problem. Male infertility occurs in 40 percent of all infertility cases. Male infertility may be due to a man's low sperm count, decreased sperm motility, or aberrant sperm morphology.
Prostate is a small gland that sits just above the rectum. It provides a good deal of the fluid in semen. As men age, the prostate gland grows larger, creating a condition called benign prostatic hypertrophy, or BPH. Ten percent of all men have some degree of prostate enlargement by age 40. By age 50, that number has grown to 50 percent and continues to increase as men get older.