Islets of Langerhans: α, β, δ cells !
- Cell
Islets are clusters of cells inside the pancreas that release insulin and glucagon into the blood to control sugar.
Updated 2026-11-01
See it in 3D: Pancreas
What it is
The endocrine pancreas is made of islets of Langerhans scattered among the exocrine acini, most plentiful in the tail. Each islet is a pale cluster of cells with many fenestrated capillaries. Beta cells are the majority and make insulin; alpha cells make glucagon and delta cells somatostatin. Loss or failure of beta cells explains type 1 and type 2 diabetes.
Structure
- On H&E: rounded islands paler than the surrounding acini, with no ducts.
- Cells lie in cords between capillaries; the neighbouring acini are basophilic at the base with pink zymogen granules at the apex.
- Immunohistochemistry tells each cell type apart by its hormone.
Function
- Keep glucose steady between and after meals.
- Insulin stores energy (glycogen, fat, protein); glucagon releases it.
- Gut incretins (GLP-1 and GIP) boost insulin release after a meal.
Islet cells
| Cell | Hormone | Effect | Tumour |
|---|---|---|---|
| β (the majority) | Insulin and amylin | Lowers glucose | Insulinoma: hypoglycemia |
| α | Glucagon | Raises glucose | Glucagonoma: mild diabetes and necrolytic migratory erythema |
| δ | Somatostatin | Restrains insulin, glucagon and gut secretions | Somatostatinoma (rare) |
| PP | Pancreatic polypeptide | Modulates appetite and pancreatic secretion | Very rare |
Markers
- Insulin
- Glucagon
- Somatostatin
- Chromogranin A
- Synaptophysin
Clinical notes
- Chronic pancreatitis destroys the acini first and later the islets too, with secondary diabetes.
- Infant of a mother with poorly controlled diabetes: fetal beta cell hyperplasia and hypoglycemia at birth.
- Pancreatic neuroendocrine tumours are recognised with chromogranin and synaptophysin.
Test yourself
Think of the answer, then tap the question to see it.
What is the most abundant cell of the islet of Langerhans and what does it secrete?
The beta cell, which secretes insulin (and amylin).
Which histologic finding defines early type 1 diabetes?
Insulitis: a T-cell infiltrate in the islets with destruction of beta cells.
What is deposited in the islets in type 2 diabetes?
Amyloid made of amylin (islet amyloid polypeptide).
See it in 3D
The structures of Durgical's 3D anatomy where it is found.
Related
- Pancreas: acini and islets
- Pineal gland and the diffuse endocrine system
- Enteroendocrine cells and GALT
Related conditions
In Pharmacology
Educational content on normal microscopic structure and its clinical relevance; no substitute for studying slides or for a health professional's advice.
Sources: 17.9 The Endocrine Pancreas (OpenStax, Rice University, 2022); 17.10 Organs with Secondary Endocrine Functions (OpenStax, Rice University, 2022).
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Representative model, for educational purposes only.