TEM #17-8 Rat Adrenal Medulla (X9,000): Shows epinephrine secreting cells. Observe that the secretory granules have a discrete limiting membrane, with the secretory material somewhat condensed within.
Review the vascular pattern of the adrenal gland. What is the significance of this vascular association of adrenal cortex with the medulla? Recall the hormones synthesized by the different zones of the cortex, and the medulla. Which cortical zone is affected most by ACTH? Which zone is influenced most by the renin-angiotensin system?
The presence of neuronal cell bodies in the medulla (you may not always find these on your slides) should remind you that the medulla is derived during development from a mass of neural crest cells that also give rise to postganglionic sympathetic neurons. The adrenal medulla may therefore be considered as a sympathetic gland storing the neurotransmitters norepinephrine and epinephrine.