The term androgen comes from the ancient Greek word andro, which means male. It designates hormones and any other compounds such as steroids, either natural or synthetic, that bind to androgen receptors and regulate the so-called male traits in humans and animals. These compounds were identified for the first time in 1936 and are produced during puberty by both boys and girls. They control the development and activity of the male sexual organs and all other physical characteristics associated with males. Androgens are a precursor of all estrogen compounds, as well as the initial steroids. Testosterone is the most important and best known androgen.
While not as famous as testosterone, androstenedione and dihydrotestosterone (DHT) are equally important in the development of males. DHT acts at the embryo level and controls the formation of the prostate, penis and scrotum. It continues to play a key role later in life, when it regulates sebum glands, prostate development and can also cause baldness. Most people think that androgens are only found in males and estrogens in females but this is not true. Both sexes have different amounts of both types of hormones. Besides androgens, there are two other types of sex hormones: progestogens (such as progesterone) and estrogens (like estradiol).
A healthy body will naturally produce the required amount of androgens. However, people who have low levels of hormones can get the rest from medication. Androgens are produced in the testes and control most aspects of male sexual traits. Women ovaries also produce androgens, in lower amounts when compared to men.
There are several types of androgens, the most important being the low-power steroids named adrenal androgens. The most common are dehydroepiandrosterone (DHEA), built from cholesterol in the adrenal cortex, a variant known as dehydroepiandrosterone sulfate (DHEA-S) and androstenedione, which is produced in the adrenal cortex, as well as male testes and female ovaries.
Testosterone is by far the best known androgen and it modulates the secondary characteristics associated with males. Dihydrotestosterone (DHT) is also very important and is generated in the skin, testes and ovaries as a metabolite of testosterone. During embryo development, DHT triggers the formation of male sexual organs like the prostate, penis and scrotum. DHT continues its role into adulthood, when it controls the growth of the prostate, the production of sebum and is one of the causes of hair loss.
Androgens have a number of roles and functions in the male body. One of the most important is the formation of testicles. Mammal's embryos develop as either makes of females and based on their genetic inheritance end up with testes or ovaries. In the presence of Y chromosomes, the embryo develops penis, scrotum and prostate. After these organs are fully grown, they continue to produce androgens, which further influence the typical male characteristics.
After the age of puberty, males start producing sperm, which continues sometimes until death. Androgen hormones play a part in this process, known as spermatogenesis. Like all hormones, balance is important. Excessive levels of androgens can stop sperm production and even lead to permanent male infertility.
A rather obscure role of androgens is to inhibit fat deposits at a cellular level. They can stop fat cells from accumulating fats, which is one of the reasons why males are generally thinner than females.
Androgens also control the development of muscular mass and explain why males are stronger than females. They influence a number of different cell types at the level of the skeletal muscles and boost the growth and expansion of these tissues. Myoblasts are the specific cells that start the hormonal signals that request the rest of the muscle to grow. The higher the level of androgens, the higher the chance for skeletal muscles to increase in size. Based on the androgen receptor levels, myotubes are created.