[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Histology](https://durgical.com/en/histology/) › [Endocrine system](https://durgical.com/en/histology/#a-endocrine) › Islets of Langerhans: α, β, δ cells

[Histology](https://durgical.com/en/histology/) · [Endocrine system](https://durgical.com/en/histology/#a-endocrine)

# 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](https://durgical.com/en/anatomy/pancreas/)

## Key points

- Beta cells: about three quarters of the islet; insulin, which lowers glucose.
- Alpha cells: about one fifth; glucagon, which raises glucose.
- Delta cells: somatostatin, which restrains the others; PP cells: pancreatic polypeptide.
- Type 1 diabetes: insulitis (T cells in the islet) and loss of beta cells.
- Type 2 diabetes: amyloid (amylin) deposits in islets and progressive beta cell failure in the face of insulin resistance.

## 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)](https://durgical.com/en/conditions/type-1-diabetes-mellitus/) | 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.

## Memory aid

In the islet, β is the majority that saves, α the minority that spends and δ the referee who quiets both.

## 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).

[Add to my cards (3)](https://durgical.app/estudiar/?add=/en/histology/islets-of-langerhans-cells/)

## See it in 3D

The structures of Durgical's 3D anatomy where it is found.

- [Pancreas](https://durgical.com/en/anatomy/pancreas/)

## Related

- [Pancreas: acini and islets](https://durgical.com/en/histology/pancreas-acini-and-islets/)
- [Pineal gland and the diffuse endocrine system](https://durgical.com/en/histology/pineal-gland-and-the-diffuse-endocrine-system/)
- [Enteroendocrine cells and GALT](https://durgical.com/en/histology/enteroendocrine-cells-and-galt/)

## Related conditions

- [Type 1 diabetes mellitus](https://durgical.com/en/conditions/type-1-diabetes-mellitus/)
- [Type 2 diabetes mellitus](https://durgical.com/en/conditions/type-2-diabetes-mellitus/)
- [Acute pancreatitis](https://durgical.com/en/conditions/acute-pancreatitis/)

## In Pharmacology

- [Insulins](https://durgical.com/en/pharmacology/classes/insulins/)

[← All of histology](https://durgical.com/en/histology/)

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](https://openstax.org/books/anatomy-and-physiology-2e/pages/17-9-the-endocrine-pancreas) (OpenStax, Rice University, 2022); [17.10 Organs with Secondary Endocrine Functions](https://openstax.org/books/anatomy-and-physiology-2e/pages/17-10-organs-with-secondary-endocrine-functions) (OpenStax, Rice University, 2022).

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Representative model, for educational purposes only.

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Source: https://durgical.com/en/histology/islets-of-langerhans-cells/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/histology/islets-of-langerhans-cells/