S cell

For the cell cycle phase, see S phase.

S cells or Secretin cells are cells which release secretin, found in the jejunum and duodenum.^[1] They are stimulated by a drop in pH to 4 or below in the small intestine's lumen. The released secretin will increase the secretion of bicarbonate (HCO₃⁻) into the lumen, via the pancreas. This is primarily accomplished by an increase in cyclic AMP that activates CFTR to release chloride anions into the lumen. The luminal Cl⁻ is then involved in a bicarbonate transporter protein exchange, in which the chloride is reabsorbed by the cell and HCO₃⁻ is secreted into the lumen. S cells are also one of the main producers of cyclosamatin.

Secretin cells in the duodenum of (A) a healthy subject, (B) a patient with celiac disease (CD), and (C) a patient with irritable bowel syndrome (IBS)

S cell
Details
Location	Jejunum and duodenum
Function	Secretin secretion
Identifiers
Latin	endocrinocytus S
TH	H3.04.02.0.00037
FMA	62936
Anatomical terms of microanatomy [edit on Wikidata]