Enterochromaffin cells

Enterochromaffin (EC) cells (Kulchitsky cells) are a type of enteroendocrine cell occurring in the epithelia lining the lumen of the gastrointestinal tract.

Function
They produce and contain about 90% of the body's store of serotonin (5-HT).

In the gastrointestinal tract, 5-HT is important in response to chemical, mechanical or pathological stimuli in the lumen. It activates both secretory and peristaltic reflexes, and activates vagal afferents (via 5-HT3 receptors) that signal to the brain (important in the generation of nausea).

Ondansetron is an antagonist of the 5-HT3 receptor and is an effective anti-emetic.

Etymology
They are called "entero" meaning related to the gut and "chromaffin" because of a chromium salt reaction that they share with chromaffin cells of the adrenal medulla (adrenal glands).

"Enterochromaffin-like cells"
Another population of chromaffin cells is found only in the stomach wall, called enterochromaffin-like cells (ECL). They look "like" EC cells but do not contain 5-HT.

ECL cells respond to acetylcholine released by the vagus nerve and they in turn release histamine, which will stimulate the G cells to produce gastric acid.