Sex Hormone

Definition - What does Sex Hormone mean?

Sex hormones are a type of a messenger molecule that takes a signal from the site where it is synthesized to a target organ through the blood stream. They are produced in the reproductive glands (testes and ovaries) and the outer area of the adrenal gland and are regulated by the hormones released by the hypothalamus and pituitary.

Estrogen and testosterone are the main sex hormones that are responsible for regulation of the sexual development and the reproductive function in both males and females. Abnormalities in sex hormone levels and their function can alter the normal reproductive function leading to infertility.

FertilitySmarts explains Sex Hormone

The production of the sex hormones by sex glands is under strict control of the brain. The hypothalamus releases gonadotropin-releasing hormone (GnRH) that stimulates the release of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) into the blood stream. These two hormones are primarily responsible for the regulation of the production of sex hormones. This regulatory axis is also known as the hypothalamus-pituitary-gonadal (HPG) axis.

Estrogen is produced in the female ovary by the granulosa and theca cells that surround the developing follicle, and to a lesser degree in other sites such as the fat tissue. Having a normal estrogen level is vital for the optimum function of the female ovarian cycle and other sexual organs. Abnormal estrogen levels can cause irregularities in ovulation and periods, resulting in female infertility.

Testosterone is the main sex hormone in males and is produced by Leydig cells in the testes. Testosterone stimulates the production of sperm in the testes and also plays a role in sexual desire and function. Abnormal testosterone levels, either due to abnormalities of testes or the brain regulation can lead to male infertility.

If an insufficient level of sex hormones in blood is the underlying cause for infertility in a couple, these hormones can be given artificially into the blood stream in the form of injections. This is called hormone replacement therapy. Sex hormone levels can also be increased by increasing the levels of LH and FSH in blood, which can be achieved through certain medications.

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