The adrenal gland consists of 2 main parts:1. an outer cortex which secretes several classes of steroid hormones;
2. an inner medulla which is the source of the catecholamines epinephrine and norepinephrine.The adrenal also has a thin outer fibrous capsule which can vary in thickness from gland to gland, and in some cases, even within the same gland.
When the adrenal gland is reviewed under the microscope, three different layers are identified in the cortex and one layer in the medulla. In the following images the yellow and orange layers represent the cortical layers and the red represents the medulla.
The cortex is divided into the 3 zones based on the arrangement of cells.
zona glomerulosa is the outer most rounded groups of cell.
zona fasciculata, is the middle column of cells and arranged radially.
zona reticularis is the innermost irregularly arranged cylindrical masses of cells.
“GFR” is a good pneumonic to remember. It stands for glomerular filtration rate but also stands for the three layers, from outer to inner, – glomerulosa, fasciculata, and reticularis.
Parts – Functional
Anatomy and Physiology of the Adrenal Glands: Parts – Imaging
In imaging it is usually not possible to differentiate between the cortex and the medulla, and we divide the adrenal into the medial and lateral limbs which are joined together at the apex of the gland.