The adrenal gland has an outer cortex and inner medulla. The cortex is divided into three concentric zones - the zona glomerulosa secretes mineralocorticoids, the zona fasiculata secretes glucocorticoids, and the zona reticulari secretes androgens. The medulla contains chromaffin cells that secrete catecholamines such as epinephrine. Diseases can result from insufficient or excessive secretion from the cortex or medulla.

2. ADRENAL GLAND
Covered with thick CT capsule from which trabeculae
extend into parenchyma, carrying blood vessels & nerves
OUTER YELLOWISH CORTEX
- Steroid- secreting
- 90% of the gland by weight
- Mesodermal mesenchyme
- Controlled in part by anterior pituitary gland
- Regulate metabolism & maintain normal electrolyte
balance
ZONA
GLOMERULOSA
mineralocorticoids
ZONA
FASICULATA
glucocorticoids
ZONA
RETICULARIS
androgens
DARK INNER MEDULLA
- Catecholamine-secreting
- Form center of the gland
- Neuroectoderm
- Richly innervated by preganglionic
sympathetic fibers
CHROMAFFIN
CELLS
catecholamines
SYMPATHETIC
GANGLION CELLS

3. Cortex
Zona glomerulosa mineralocorticoids (aldosterone)
Zona fasiculata glucocorticoids (cortisol)
Zona reticularis Androgens (dehydroepiandosterone(DHEA))
Medulla
catecholamines
(epinephrine & norepinephrine)

4. • Cells arranged into three concentric zones
– differentiated based on the pattern produced by cords of cells
– boundaries between zones are indistinct
ZONA GLOMERULOSA: narrow outer zone that constitutes up to 15% of the cortical volume
ZONA FASICULATA: thick middle zone that constitutes nearly 80% of the cortical volume
ZONA RETICULARIS: inner zone that constitutes only 5% to 7% of the cortical volume but is
thicker than the glomerulosa because of its more central location

5. • small columnar cells
• arranged in closely packed ovoid clusters & curved columns
• spherical nuclei appear closely packed and stain densely
• rich network of fenestrated sinusoidal capillaries surrounds each cell cluster
• lipid droplets are sparse
• SECRETES MINERALOCORTICOIDS (ALDOSTERONE, DEOXYCORTICOSTERONE)
– Maintain fluid & electrolyte balance

6. • large polyhedral cells
• arranged in long straight cords, one or two cells thick, separated
by sinusoidal capillaries
• lightly staining spherical nucleus
• Binucleate cells are common
• numerous lipid droplets
– contain neutral fats, fatty acids, cholesterol, & phospholipids
(precursors for the steroid hormones)
• SECRETES GLUCOCORTICOIDS (CORTISOL, CORTICOSTERONE)
– Regulate metabolism of carbohydrate, protein & lipid (gluconeogenesis, proteolysis, lipolysis)
– Suppress inflammation & immune response
– Impair healing process

7. • dark acidophilic cells
– abundant lipofuscin pigment granules
• Smaller cells compared to cells in zona fasciculata, nuclei are more deeply stained
– less cytoplasm; thus the nuclei appear more closely packed.
• arranged in anastomosing cords, separated by fenestrated capillaries
• cells have relatively few lipid droplets
• SECRETES ANDROGENS (DEHYDROEPIANDOSTERONE, ANDROSTENEDIONE)
– Weak masculinizing effect
– Libido, body hair (female)

8. • Consist of:
– Chromaffin cell (most abundant cell)
– CT
– Sinusoidal blood capilaries
– Nerves
• Myelinated
– Sympathetic ganglion cells
• round or polygonal with prominent
nuclei
• May be in cluster

9. • Pheochromocytes
• Large, pale-staining epithelioid cells
• Organized in ovoid clusters & short interconnecting cords
• Intimate relation with blood capillaries
• Granular cytoplasm due to hormone-containing granules can be observed
– Stain intensely with Chromaffin salts
• SECRETES CATECHOLAMINES (ADRENALINE, NORADRENALINE)
– Augment sympathetic system activity
– Major role in acute response to stress

10. Chromaffin cells arranged in clusters,
usually around medullary veins
Ganglion cells
(round or polygonal with
prominent nuclei)

11. • Insufficient cortical secretion
– Addison’s disease
• Excessive cortical secretion
– Cushing’s syndrome  hypercortisolism
– Masculinization (virilism)  excessive adrogens in women
– Feminization  excessive estrogens in men
– Adrenogenital syndrome  excessive sex hormone in children

12. • Abnormal medullary secretion
– Hyposecretion
• Not much problem if sympathetic function is normal
• Some attenuation of acute response to stress
– Hypersecretion
• Pheochromocytoma  benign tumours of adrenal medulla
The tumor cells in pheochromocytoma may be arranged in
alveolar (nesting), trabecular, solid/diffuse, or mixed
patterns. Alveolar pattern is shown here

14. • Histology of adrenal gland
– http://arbl.cvmbs.colostate.edu/hbooks/pathphys/endocrine/adrenal/histo_overview.html
• Histology: A Text and Atlas
by Ross M.H. and Pawlina W.
– https://www.inkling.com/read/histology-michael-ross-and-wojciech-pawlina-6th/chapter-
21/adrenal-glands#4652fc36484946c9a323b2baa04cd87b
• DiFiore's Atlas of Histology with Functional Correlations
By Victor P. Eroschenko, Mariano S. H. di Fiore
– http://books.google.com.my/books?id=sH87M12QswcC&pg=PA463&lpg=PA463&dq=histologi
cal+structure+adrenal+gland%27s+correlation+with+function&source=bl&ots=zP80SNqbej&si
g=Cxhx-znWfbs0TdVCSrUFGTdCxBk&
hl=en&sa=X&ei=LJwAVOapO5CcugSGuoLQDg&redir_esc=y#v=on
epage&q=histological%20structure%20adrenal%20gland's%20correlation%20with%20functio
n&f=false
• Adrenal Medulla Development Movie
– http://embryology.med.unsw.edu.au/embryology/index.php?title=Adrenal_Medulla_Develop
ment_Movie