Study Guide for Histology of Adrenal Gland

Stroma consists of:

a) Thick dense connective tissue (CT) capsule

b) Thin trabeculae/ septa

Parenchyma consists of:

I) CORTEX (90%);

- Steroid-secreting cells
- Originate from the mesodermal mesenchyme
- Consist of 3 layers
- Table 1 shows the comparison of the histological features between the 3 layers of the adrenal cortex

Table 1: Histological comparison between 3 layers of the adrenal cortex

HISTOLOGICAL FEATURES	ZONA GLOMERULOSA (15%)	ZONA FASICULATA (80%)	ZONA RETICULARIS (5%)
Arrangement	Ovoid cluster + curved column	Long straight cord (1/ 2 cell thick)	Anastomosing cord (network of irregular cords)
Diagram
Surrounded by:	Fenestrated sinusoidal capillaries	Fenestrated sinusoidal capillaries	Sinusoidal capillaries
Shape	Small columnar/ pyramidal cells	Large polyhedral cells	Small polyhedral cells (compared to Zona Fasciculata)
Cytoplasm	Poor staining (high sER + lipid droplets)	Poor staining (higher sER + lipid droplets) (Foamy appearance)	Darker (less sER + few lipid droplets +lipofuscin)
Staining	Moderately acidophilic	Poor acidophilic	Distinct acidophilic
Nuclei	Densely stained spherical nucleus Prominent nucleolus	Lightly stained spherical nucleus Binucleated (some)	Deeply stained nucleus
Function: a)secretes b) stimulated by	"SALT" -Mineralocorticoid (aldosterone) angiotensin II	"SUGAR" Glucocorticoid (cortisol) -Small amount gonadocorticoid (androgens) negative feedback ACTH	"SEX" Gonadocorticoid (DHEA) -Small amount of glucocorticoid (cortisol) negative feedback ACTH

II) MEDULLA (10%);

- Catecholamine-secreting cells
- Originate from the neural crest cell of neuroectoderm
- Contains:

1. Chromaffin cells (majority)

Table 2 shows the histological features of the Chromaffin cell

2. Ganglion cells (minority)

3. Sinusoidal capillaries

4. Adrenomedullary veins/ Medullary veins/ Central adrenomedullary veins

Table 2: Histological features of the Chromaffin cells

HISTOLOGICAL

FEATURES

CHROMAFFIN CELL (Neuroendocrine Cell)

Definition

Sympathetic postganglionic neurons (specialized secretory cells containing granules)

Arrangement

Short interconnecting cord/ovoid clusters

Separated by

Sinusoidal capillaries (larger gaps and pores)

Shape

Large + oval/polyhedral

Type

* These 2 populations can only be differentiated using TEM

Diagram

*Disclaimers: The color used in the drawings are for illustration purposes only and may not be an exact

representation of the actual color in the photomicrograph