The zona reticularis is the innermost layer of the adrenal cortex

Adrenal cortex

Situated along the perimeter of the adrenal gland, the adrenal cortex mediates the stress response through the production of mineralocorticoids and glucocorticoids, including aldosterone and cortisol respectively. It is also a secondary site of androgen synthesis.-Layers:Notably, the reticularis in...

, lying deep to the zona fasciculata

Zona fasciculata

The zona fasciculata constitutes the middle zone of the adrenal cortex, sitting directly beneath the zona glomerulosa. Constituent cells are organized into bundles or "fascicles"....

 and superficial to the adrenal medulla

Adrenal medulla

The adrenal medulla is part of the adrenal gland. It is located at the center of the gland, being surrounded by the adrenal cortex. It is the innermost part of the adrenal gland, consisting of cells that secrete epinephrine , norepinephrine , and a small amount of dopamine in response to...

. The cells are arranged cords that project in different directions giving a net-like appearance (L. reticulum - net).

Cells in the zona reticularis produce precursor androgens including dehydroepiandrosterone

Dehydroepiandrosterone

5-Dehydroepiandrosterone is a 19-carbon endogenous steroid hormone. It is the major secretory steroidal product of the adrenal glands and is also produced by the gonads and the brain. DHEA is the most abundant circulating steroid in humans....

 (DHEA) and androstenedione

Androstenedione

Androstenedione is a 19-carbon steroid hormone produced in the adrenal glands and the gonads as an intermediate step in the biochemical pathway that produces the androgen testosterone and the estrogens estrone and estradiol.-Synthesis:Androstenedione is the common precursor of male and female sex...

 from cholesterol

Cholesterol

Cholesterol is a complex isoprenoid. Specifically, it is a waxy steroid of fat that is produced in the liver or intestines. It is used to produce hormones and cell membranes and is transported in the blood plasma of all mammals. It is an essential structural component of mammalian cell membranes...

. DHEA is further converted to DHEA-sulfate via a sulfotransferase

Sulfotransferase

Sulfotransferases are transferase enzymes that catalyze the transfer of a sulfate group from a donor molecule to an acceptor alcohol or amine. The most common sulfate donor is 3'-phosphoadenosine-5'-phosphosulfate...

, SULT2A1

SULT2A1

Alcohol sulfotransferase is an enzyme that catalyzes the sulfate conjugation of primary and secondary alcohols including many hormones, neurotransmitters, drugs, and xenobiotic compounds.- Family members :...

. These precursors are not further converted in the adrenal cortex if the cells lack 17Beta Hydroxysteroid dehydrogenase

17Beta Hydroxysteroid dehydrogenase

The 17β-hydroxysteroid dehydrogenases are a group of alcohol oxidoreductases which catalyse the dehydrogenation of 17-hydroxysteroids in steroidogenesis.Note that the major reactions catalysed by 17β-HSD The 17β-hydroxysteroid dehydrogenases (17β-HSD enzymes) are a group of alcohol oxidoreductases...

. Instead, they are released into the blood stream and taken up in the testis and ovaries to produce testosterone

Testosterone

Testosterone is a steroid hormone from the androgen group and is found in mammals, reptiles, birds, and other vertebrates. In mammals, testosterone is primarily secreted in the testes of males and the ovaries of females, although small amounts are also secreted by the adrenal glands...

 and the estrogens respectively.

In humans the reticularis layer does contain 17 alpha-hydroxylase; this hydroxylates pregnenolone, which is then converted to cortisol by a mixed function oxidase. In rodents, the lack of 17alpha-hydroxylase results in the synthesis of corticosterone

Corticosterone

Corticosterone is a 21-carbon steroid hormone of the corticosteroid type produced in the cortex of the adrenal glands.-Roles:In many species, including amphibians, reptiles, rodents and birds, corticosterone is a main glucocorticoid, involved in regulation of fuel, immune reactions, and stress...

 instead of cortisol

Cortisol

Cortisol is a steroid hormone, more specifically a glucocorticoid, produced by the adrenal gland. It is released in response to stress and a low level of blood glucocorticoids. Its primary functions are to increase blood sugar through gluconeogenesis; suppress the immune system; and aid in fat,...

as in the human.