The inner medulla of the adrenal gland contains which granules that produce epinephrine and norepinephrine?

• A. Zymogen granules
• B. Chromaffin granules
• C. Lipofuscin granules
• D. Secretory granules

Answer: (B)

The adrenal medulla houses chromaffin cells that synthesize and store catecholamines—epinephrine and norepinephrine—in dense-core secretory granules. These granules are specialized to package and release these neurotransmitters into the bloodstream when the body needs a rapid fight-or-flight response. The name chromaffin granules comes from their brown staining with chromaffin reagents, which oxidize the catecholamines contained inside. This makes them a histological hallmark of the adrenal medulla. Other granule types mentioned, like zymogen granules or lipofuscin, belong to different tissues or contexts and don’t specifically describe the catecholamine-storage granules of the medulla. While “secretory granules” is a broad term, the specific granules in this location are chromaffin granules.