Adrenal gland histology

00:00 / 00:00


Adrenal gland histology

USMLE® Step 1 questions

0 / 1 complete


USMLE® Step 1 style questions USMLE

of complete

A researcher is studying the function of the adrenal gland on a molecular level. Which of the following hormones are secreted by the region labeled B in the histological image of a normal adrenal gland shown below?


The adrenal glands are a pair of endocrine glands that are located just above or superior to the kidneys and are also in the retroperitoneal space of the abdominal cavity.

The left gland has a semilunar shape and the right gland is flattened and more triangular in appearance.

The adrenal glands are covered by a capsule made of thick connective tissue.

The parenchymal tissue has two main regions, the adrenal cortex and the adrenal medulla.

The cortex is the large outer region of the adrenal gland.

The cortex can be further divided into three zones that each secrete a different class of steroid hormones.

Starting with the most superficial zone: the zona glomerulosa secretes mineralocorticoids, the zona fasciculata secretes primarily glucocorticoids, and the zona reticularis secretes primarily gonadocorticoids, or sex hormones.

The adrenal medulla is the region that’s most centrally located and visibly distinct from the cortex.

The medulla is responsible for secreting the catecholamines: epinephrine and norepinephrine.

If we zoom in further, we can see some of the blood vessels of the adrenal gland.

Just outside of the capsule, there are small afferent blood vessels that are branches of the suprarenal arteries that supply blood to the adrenal gland.

And within the medulla, there are the large medullary veins that drain blood into the suprarenal veins.

Now, let’s take a closer look at the outermost layer of the adrenal cortex, the zona glomerulosa.

This layer is just beneath the capsule and comprises about 15 percent of the cortex.

The secretory cells are arranged in ovoid or glomerulus-like clusters that are separated by fibrous trabeculae that extends from the capsule.

The individual cells are either columnar or pyramidal with round nuclei, and a lipid-filled cytoplasm that gives the cytoplasm its pale “foamy” appearance.


Adrenal gland histology is the study of the microscopic structures of tissues of the adrenal gland. The adrenal gland is a small, triangular-shaped organ that sits on top of each kidney. It has two parts: the cortex and the medulla.

The cortex is made up of three layers: the zona glomerulosa, the zona fasciculata, and the zona reticularis. The medulla contains sympathetic nerve cells that release adrenaline (epinephrine) and noradrenaline (norepinephrine) into the bloodstream.


  1. "Histology. A Text and Atlas" Wolters Kluwer (2018)
  2. "Wheater's Functional Histology" Churchill Livingstone (2013)
  3. "Junqueira's Basic Histology: Text and Atlas, Fourteenth Edition" McGraw-Hill Education / Medical (2015)
  4. "Robbins Basic Pathology" Elsevier (2017)
  5. "Diagnostic Immunohistochemistry" Elsevier (2021)
  6. "Cytology" Saunders (2013)
  7. "The Product of the CYP11B2 Gene Is Required for Aldosterone Biosynthesis in the Human Adrenal Cortex" Molecular Endocrinology (1991)
  8. "Early steps in steroidogenesis: intracellular cholesterol trafficking" Journal of Lipid Research (2011)
  9. "Classic congenital adrenal hyperplasia and puberty" European Journal of Endocrinology (2004)

Copyright © 2023 Elsevier, its licensors, and contributors. All rights are reserved, including those for text and data mining, AI training, and similar technologies.

Cookies are used by this site.

USMLE® is a joint program of the Federation of State Medical Boards (FSMB) and the National Board of Medical Examiners (NBME). COMLEX-USA® is a registered trademark of The National Board of Osteopathic Medical Examiners, Inc. NCLEX-RN® is a registered trademark of the National Council of State Boards of Nursing, Inc. Test names and other trademarks are the property of the respective trademark holders. None of the trademark holders are endorsed by nor affiliated with Osmosis or this website.