Adrenal Gland anatomy and histology

Question 0

Fetal cortex

Answer 0

Week 20-> adrenals mostly fetal cortex
Larger than kidneys
At birth they lack some enzymes but are responsive to ACTH
Adrenal hormones are involved in lung maturation
Gut closure to IgG transport is under the influence of corticosteroids

Question 1

Embryological origin of cortex and medulla

Answer 1

Each gland is two separate endocrine organs
Outer cortex-> coelomic mesothelium-> controlled by adenohypophysis-> produces steroid hormones
Inner medulla-> developed from neural crest (neuroectoderm)-> producing catecholamines-> under nervous control

Question 2

Cortex histology

Answer 2

Zona reticularis-> cells arranged in cords separated by sinusoids, cells most densely packed
Zona fasciculata-> sinusoids between columns of cells, obvious capillaries-> all cells have access to blood stream
Zona glomerulusa-> columnar or ovoid cells, more gaps! circles

Question 3

Medulla histology

Answer 3

Dark staining cells
Chromaffin cells stain yellow
Cells arranged in groups with rich blood supply

Question 4

Blood supply

Answer 4

Capsular artery
Corticol arterioles down into zona glomerulusa
Capillary beds around circular areas of cells
Or medullary artery that goes straight down to medulla
Capillary bed-> straight capillaries down zona fasciculata
Sinusoids in zona retiulata
Chromatin cells surrounded by blood in medulla
Leaves through veins

Question 5

Ultra structure of the medulla

Answer 5

Lots of rough ER and Golgi
Lots of black secretory granules
Normal mitochondria
Peptide secreting cells

Question 6

Ultra structure of the cortex

Answer 6

Smooth ER-> lipid metabolism for steroid production
Lipid droplets-> storage for steroid synthesis
Tubular cristae in mitochondria-> larger than in medulla and more of them

Question 7

Innervation

Answer 7

Sympathetic preganglionic fibre synapse directly on to adrenal medullary cells
Causes an increase in Ca in the cell

Question 8

Comparison between post ganglion autonomic neurones and adrenal medullary cells

Answer 8

Both derived from neural crest
Both produce adrenaline and noradrenaline
Sympathetic neurones delivery the agent directly to the effector, cells of the adrenal medulla deliver agent indirectly through blood stream
Both cause effect by becoming depolarised