Expansion
Crypt base in gut, basal layer in epidermis, limbus in cornea
Expansion
| Tissue | Niche |
|---|---|
| Small intestine and colon | Base of the crypts of Lieberkuhn |
| Epidermis | Stratum basale, and the bulge region of the hair follicle |
| Cornea | Limbus, at the corneoscleral junction |
| Bone marrow | Endosteal and perivascular niches |
| Liver | Canals of Hering (oval cells), plus hepatocyte replication |
| Skeletal muscle | Satellite cells beneath the basal lamina |
| Brain | Subventricular zone and hippocampal dentate gyrus |
| Testis | Spermatogonia at the basement membrane |
The clinical importance is that niche destruction is what makes damage permanent.
- Limbal stem cell failure after chemical burns causes conjunctivalisation of the cornea and blindness that corneal grafting alone cannot correct, requiring limbal stem cell transplantation
- Full thickness burns destroy the follicular bulge as well as the basal layer, which is why they cannot re-epithelialise and require grafting, whereas partial thickness burns heal from surviving adnexal structures
- Radiation damage to intestinal crypt stem cells causes the gastrointestinal syndrome of acute radiation sickness