CorpusHuman Anatomy
DigestiveGland

Intestinal crypts

Glandulae intestinales

Also known as: crypts of Lieberkühn, intestinal glands

Intestinal crypts (of Lieberkühn) are simple tubular glands that dip from the mucosal surface down to the muscularis mucosae. They hold the stem cells that renew the epithelium, and they secrete fluid, mucus and antimicrobial proteins.

Show on body map Intestinal Villus and Absorption Wall of the Gastrointestinal Tract

Overview

In the small intestine the crypts open between the bases of the villi. In the large intestine they open on the flat mucosal surface, where they are straight, closely packed and very rich in goblet cells.

At the crypt base, Lgr5⁺ crypt-base columnar stem cells sit between Paneth cells, which secrete antimicrobial proteins and supply niche signals (Wnt, EGF and Notch ligands). Above them, rapidly dividing transit-amplifying cells produce all the epithelial lineages: enterocytes, goblet cells, enteroendocrine cells (I, S, K, L and serotonin-secreting enterochromaffin cells) and tuft cells. This is the fastest-renewing tissue in the adult body.

Crypt enterocytes are the main secretory cells of the intestine. Cl⁻ enters basolaterally on the Na⁺-K⁺-2Cl⁻ co-transporter (NKCC1) and leaves apically through CFTR. Na⁺ and water follow through the paracellular pathway. The result is about 1.8 L a day of isotonic, slightly alkaline intestinal juice, which keeps luminal contents fluid and flushes the crypts.

Location

Throughout the mucosa of the small and large intestine and the appendix, between and below the villi.

Parts & subdivisions

  1. Stem cell zone
    Lgr5⁺ stem cells at the crypt base, alternating with Paneth cells.
  2. Paneth cells
    Granule-filled defensive cells at the crypt base of the small intestine.
  3. Transit-amplifying zone
    Rapidly proliferating progenitors in the lower and middle crypt.
  4. Enteroendocrine cells
    Scattered hormone-secreting cells (CCK, secretin, GIP, GLP-1, serotonin and others).

Anatomy

Histology

Simple tubular glands lined by simple columnar epithelium, with Paneth cells at the base in the small intestine and many goblet cells in the colon.

Function

  • Renew the intestinal epithelium every 3–5 days.
  • Secrete about 1.8 L of intestinal juice a day (CFTR-dependent Cl⁻ and water).
  • Antimicrobial defence (Paneth cells) and mucus production (goblet cells).
  • Endocrine signalling.

Clinical significance

Cholera and secretory diarrhoea

Cholera toxin ADP-ribosylates Gsα, which permanently activates adenylate cyclase. The rise in cAMP opens CFTR, causing massive Cl⁻ and water secretion ("rice-water" stools, up to tens of litres a day). Because Na⁺–glucose co-transport (SGLT1) still works, oral rehydration solution is life-saving.

Cystic fibrosis

Defective CFTR leaves the crypt and duct secretions dehydrated and viscous. This causes meconium ileus in newborns, distal intestinal obstruction syndrome and pancreatic insufficiency.

Crypt pathology

Crypt abscesses are typical of ulcerative colitis, and crypt hyperplasia of coeliac disease. Mucositis is the price of the rapid crypt cell division that cytotoxic chemotherapy targets.

Compiled from standard anatomy and physiology references — see the Digestive System sources. For education only; not medical advice.