Adrenal Gland Histology Flashcards
What does the cortex of the adrenal gland originate from?
Mesodermal
Develops from celomic epithelium of the posterior abdominal wall
What does the medulla of the adrenal gland originate from?
Ectodermal
Develops from neural crest cells
By the eight week of fetal development, the cortical elements have differentiated into what?
Thin outer definitive cortex and a thicker inner fetal cortexx
What does the fetal cortex actively produce?
fetal steroids during gestation but involutes rapidly after birth
What are adrenocortical rests?
Occur in up to 50% of newborn infants
Tend to atrophy and disappear early postpartum period
Can be found along path of embryonic migration of adrenal cortex
Describe accessory adrenocortical nodules
minor developmental anomalies arising from partly or completely detached rests of the coelomic epithelial primordia from which the adrenal cortex is derived
Most frequently located in contact with the capsule at one pole of adrenal but can occur completely separated in the retroperitoneal fat
Describe the development of adrenal zones
occurs slowly after birth, in parallel with regression of fetal cortex
Distinct zonae glomerulosa and fasiculata present at birth
Zona reticularis develops during the first year of life
medullary elements, derived from __________, migrate forward to ________ and paravertebral regions and along the adrenal vein toward the medial aspect of the developing ___________.
Neural crests
para-aortic
adrenal fetal cortex
During the early stage of gestation, the adrenal cortex synthesizes ____________, a precursor of the synthesis of estrogen by the _________.
dehydroepiandrosterone (DHEA)
Placenta
A lack of ________________ activity prevents the synthesis of progesterone, glucocorticoids and androstenedione
3 beta-hydroxysteroid dehydrogenase (3B-HSD)
The interactions between the fetal adrenal cortex and the placenta is known as the __________.
fetoplacental unit
3B-HSD Congenital adrenal hyperplasia is an __________ form of CAH. It results from a mutation in the gene for ___________.
uncommon
3 beta- HSD type II
What are the clinical presentations of 3 beta- HSD CAH?
Incomplete loss of 3 beta - HSD Type II
Virilization of genetically female infants and undervirilization of genetically male infants
3B - HSD CAH is a form of ______ hypoadrenalism, and is the the only form of CAH that can cause___________ in both genetic sexes.
primary
Ambiguous genitalia
During pregnancy, what are the sources of glucocorticoids for the fetus?
either of maternal origin or synthesized from placental progesterone by the fetus
What are the three main developmental events that require glucocorticoids?
- production of surfactant by type II alveolar cells after eight month of fetal life
- development of functional hypothalamopituitary axis
- induction of thymic involution
Each gland consists of a _____ outer cortex (__%) and a _____ inner medulla (__%)
Yellowish
80-90%
Reddish
10-20%
The adrenal cortex is of _______ origin and produces ______.
mesodermal
steroid hormones
The adrenal medulla is of ________ origin and produces __________.
Neuroectodermic
Catecholamines
The adrenal cortex consists of three concentric zones:
- outermost layer of the cortex: zona glomerulosa
- middle layer: zona fasiculata
- innermost: zona reticularis
What does the zona glomerulosa produce and to what stimulus ?
mineralocorticoids, mainly aldosterone
in response to Angiotensin II also ACTH
Describe the histology of zona glomerulosa
lies under capsule and is 10-15% of cortex
cells aggregate into glomerulus-like arrangement and have a moderate amount of lipid droplets in the cytoplasm
Zona glomerulosa lacks the enzyme ___________, cant produce sex steroids or _______.
17alpha-hydroxylase (CYP17)
cortisol
Aldosterone stimulates the retention of ____, ______ in kidneys, and renal secretion of ____ and _____.
Na, H2O
K and H
What does the zona fasiculata secrete?
glucocorticoids and androgens
Describe the histology of zona fasiculata
75% of cortex
cells contain many lipid droplets of cholesterol (precursor) in cytoplasm
Cells appear vacuolated (foamy appearance)
Spongiocytes
Cuboid cells: steroid-producing cell arranged in longitudinal cords separated by cortical fenestrated capillaries/sinusoids
The adrenal glands are highly vascularized. What are the aa that supply the glands?
Superior suprarenal aa - inferior phrenic a
Middle suprarenal aa - abdominal aorta
Inferior suprarenal aa - renal a
What part of the adrenal cortex contains 17-alpha hydroxylase? What is it necessary for?
ZF and ZR
Necessary for production of glucocorticoids - cortisol
What can be found in ZF and ZR that is required for the production of sex hormones?
17, 20-hydroxylase
Cortisol (is/isnt) stored in cells of ZF and ZR. New synthesis is stimulated by ________.
isnt
ACTH
Cortisol is converted in __________ to cortisone
hepatocytes
What are the two major effects of cortisol?
Metabolic effect: stimulates gluconeogenesis to increase the [glucose] in blood
Anti-inflammatory effect: suppresses tissue responses to injury and decreases cellular and humoral immunity
Zona fasciculata is often associated with ________ production
glucocorticoid - mainly cortisol
The zona reticularis is often associated with ______ production
androgen
Describe the histology of zona reticularis
innermost layer of the cortex: 5-10% of total volume
Cells arranged in irregular cords that form an anastomosing network
Secrete glucocorticoids and androgens
What is the primary sight of adrenal sex hormone production?
zona reticularis, although cells of the zona F can synthesize androgens
What are the predominant androgens produced by the cortex of the adrenal gland ?
DHEA aand androstenedione
Although DHEA and androstenedione are weak androgen, they can be converted into what?
testosterone and even to estrogen in peripheral tissue
The adrenal gland is the major source of _____ in women. What do they stimulate?
androgens
Stimulate the growth of pubic and axillary hair during puberty
Describe Chromaffin cells
Composed of polyhedral cells arranged in cords or clumps
Regarded as modified sympathetic postganglionic neurons without postganglionic axons
Derived from neural crest
Secretes EP, NE
What did chromaffin cells lose during embryonic development?
axons and dendrites and become secretory cells
Modified sympathetic postganglionic neurons w/o postgangionic axons
What is the adrenal medulla innervated by?
sympathetic preganglionic fibers that release ACh
How are catecholemines different from neurotransmitters?
Catecholamines are secreted into the blood instead of being secreted into a synapse
Catecholemines are secreted in response to ___________ reactions. What are the effects?
intense emotional
Defensive reaction to stress
Increase heart rate
Dilates blood vessels supplying cardiac and skeletal mm
Bronchiole dilation
Vasoconstriction of blood vessels supplying GI tract, kidneys, skin
All three adrenal aa enter the adrenal gland capsule and for an ____________
arterial plexus
What are the three sets of branches that emerge from the arterial plexus of the adrenal gland?
Subcapsular plexus
Short cortical aa
Long cortical aa
What does the subcapsular plexus supply?
the capsule
What does the short cortical aa supply? What is its pathway
enters the cortex forming straight fenestrated capillaries/sinusoids, percolating btwn the zonae glomerulosa and fasiculata, and forming a capillary network in the ZR before entering the medulla
What does the long cortical aa supply?
Medullar aa travel w/o branching and supplying blood only to the medulla
Medulla has direct blood supply from ________ as well as _______ from the cortex.
long cortical aa
Sinusoids
What can a tumor in ZG cause?
excessive secretion of aldosterone
rare condition: primary aldosteronism/Conn’s syndrome
What is a more common cause of hyperaldosteronism?
increase in renin secretion: secondary hyperaldosteronism
What is Cushing’s disease caused by?
ACTH-producing tumor of the anterior hypophysis
70% of endogenous cases of cushings
What hormone levels are expected in Cushing’s disease?
increase in aldosterone, cortisol, adrenal androgen production
What is Cushing’s syndrome
A functional tumor of the adrenal cortex that results in overproduction of cortisol, as well as aldosterone and adrenal androgens
15% of endogenous cases of Cushings
What are the exogenous causes of Cushings syndrome?
Taking medicines containing glucocorticoids, such as hydrocortisone
What is Addison’s disease?
a chronic destruction of adrenal cortex by an autoimmune process or tuberculosis
Cortisol deficiency leads to ACTH secretion increase
What are the clinical manifestations of Addison’s disease?
Increase in skin pigmentation, in particular in the skin folds and gums due to ACTH increase
Loss of Mineralcorticoids leads to hypotension and circulatory shock
Deficient cortisol causes muscle weakness
What are the signs of Addison’s disease?
weight loss hyperpigmentation hypotension thinning of axillary and pubic hair vitiligo
What are the symptoms of Addison’s disease?
fatigue, anorexia, syncope, postural dizziness, nausea, vomiting, diarrhea, constipation, abdominal pains, myalgias, decrease libido
What is pheochromocytoma?
Benign tumor of chromaffin cells
25% familial
What occurs with pheochromocytoma?
Episodic secretions of EP and NE
Excessive catecholamine secretion ->hypertension or cardiac arrhythmias
What are the signs and symptoms of pheochromocytoma?
SNS hyperactivity: elevated HR, BP, palpitations, diaphoresis, anxiety, headaches, nausea, pallor
Hatfield-McCoy Feud: apparently von hippel-landau has pheochromacytomas that make you want to fuck ppl up
