The zona reticularis is a part of the endocrine system's adrenal glands, and it consists of irregularly shaped and disorganized cells that are responsible for secreting a type of steroids called androgens, specifically one called androstenedione. After androstenedione is secreted by the zona reticularis, it is converted by surrounding tissues into testosterone. The effects of this testosterone are negligible in men because of the large amounts of testosterone that are secreted by the testes. In women, the effects of this testosterone are slight but noticeable.
Testosterone that is secreted by the zona reticularis is responsible for stimulating sex drive in women. It also causes pubic and axillary hair growth. If the zona reticularis is creating too much testosterone, a woman can have excessive facial and body hair, acne, an increased sex drive, regression of breast tissue or a loss of regular menstrual cycles.
The zona reticularis is located in a part of the adrenal gland called the adrenal cortex. One adrenal gland is located at the top of each kidney, near its superior pole. This gland is made up of two components; the outer part is called the cortex, and the inner part is called the medulla. The zona reticularis is the innermost part of the cortex, the middle layer is called the zona fasciculata, and the outermost layer is called the zona glomerulosa. Adrenal glands are part of the endocrine system, which is responsible for regulating different processes in the body by secreting hormones.
In addition to the testosterone that is secreted by the zona reticularis, other hormones are secreted by the other layers of the adrenal cortex. The zona glomerulosa secretes a steroid called aldosterone that regulates the reabsorption rates of sodium and potassium ions, which ultimately affect the ability of the kidney to reabsorb water. Cortisol is secreted by the zona fasciculata, and it is responsible for increased protein and fat breakdown, increased glucose production and decreased inflammation. It also is important in the maturation of fetal lungs.
The other part of the adrenal gland, the medulla, also is important for helping the body function properly. The medulla is responsible for secreting epinephrine and norepinephrine, which prepare the body for action. This effect does not last long, because these hormones are quickly metabolized by the body. The release of these hormones can be triggered by things such as emotional excitement, injury, stress and low blood glucose levels.