The zona reticularis (sometimes, reticulate zone) is the innermost layer of the
adrenal cortex
The adrenal cortex is the outer region and also the largest part of the adrenal gland. It is divided into three separate zones: zona glomerulosa, zona fasciculata and zona reticularis. Each zone is responsible for producing specific hormones. I ...
, lying deep to the
zona fasciculata and superficial to the
adrenal medulla
The adrenal medulla () is the inner 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 chromaffin cells that secrete catecho ...
. 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
An androgen (from Greek ''andr-'', the stem of the word meaning ) is any natural or synthetic steroid hormone that regulates the development and maintenance of male characteristics in vertebrates by binding to androgen receptors. This includes ...
including
dehydroepiandrosterone
Dehydroepiandrosterone (DHEA), also known as androstenolone, is an endogenous steroid hormone precursor. It is one of the most abundant circulating steroids in humans. DHEA is produced in the adrenal glands, the gonads, and the brain. It funct ...
(DHEA) and
androstenedione from
cholesterol
Cholesterol is the principal sterol of all higher animals, distributed in body Tissue (biology), tissues, especially the brain and spinal cord, and in Animal fat, animal fats and oils.
Cholesterol is biosynthesis, biosynthesized by all anima ...
. DHEA is further converted to
DHEA-sulfate via a
sulfotransferase,
SULT2A1.
These precursors are not further converted in the adrenal cortex if the cells lack
17β-Hydroxysteroid dehydrogenase. Instead, they are released into the blood stream and taken up in the
testicles and
ovaries
The ovary () is a gonad in the female reproductive system that produces ova; when released, an ovum travels through the fallopian tube/oviduct into the uterus. There is an ovary on the left and the right side of the body. The ovaries are endocr ...
to produce
testosterone
Testosterone is the primary male sex hormone and androgen in Male, males. In humans, testosterone plays a key role in the development of Male reproductive system, male reproductive tissues such as testicles and prostate, as well as promoting se ...
and the
estrogens respectively.
ACTH partially regulates
adrenal androgen
An androgen (from Greek ''andr-'', the stem of the word meaning ) is any natural or synthetic steroid hormone that regulates the development and maintenance of male characteristics in vertebrates by binding to androgen receptors. This includes ...
secretion, also
CRH.
In humans, the reticularis layer does contain
17α-hydroxylase; this hydroxylates pregnenolone, which is then converted to cortisol by a mixed function oxidase. Deficiency of 17α-hydroxylase results in low blood levels of estrogens, androgens, and cortisol, and the resultant compensatory increases in adrenocorticotrophic hormone stimulates the production of
11-deoxycorticosterone and
corticosterone
Corticosterone, also known as 17-deoxycortisol and 11β,21-dihydroxyprogesterone, is a 21-carbon steroid hormone of the corticosteroid type produced in the cortex of the adrenal glands. In the very rare case of congenital adrenal hyperplasia due ...
. In
rodents
Rodents (from Latin , 'to gnaw') are mammals of the order Rodentia ( ), which are characterized by a single pair of continuously growing incisors in each of the upper and lower jaws. About 40% of all mammal species are rodents. They are n ...
, the lack of 17α-hydroxylase results in the compensatory synthesis of
corticosterone
Corticosterone, also known as 17-deoxycortisol and 11β,21-dihydroxyprogesterone, is a 21-carbon steroid hormone of the corticosteroid type produced in the cortex of the adrenal glands. In the very rare case of congenital adrenal hyperplasia due ...
instead of
cortisol
Cortisol is a steroid hormone in the glucocorticoid class of hormones and a stress hormone. When used as medication, it is known as hydrocortisone.
Cortisol is produced in many animals, mainly by the ''zona fasciculata'' of the adrenal corte ...
.
References
External links
*
* - "Adrenal Gland"
{{Adrenal gland
Adrenal gland