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# Retina: the ten layers, rods and cones

- Organ

The retina is nerve tissue that turns light into signals. Under the microscope it shows ten layers, with the light sensors at the outer edge.

Updated 2026-11-01

**See it in 3D:** [Retina](https://durgical.com/en/anatomy/retina/)

## Key points

- Outer to inner: pigment epithelium, photoreceptors, outer limiting, outer nuclear, outer plexiform, inner nuclear, inner plexiform, ganglion cells, nerve fibres, inner limiting.
- Retinal detachment separates the neural retina from the pigment epithelium, a space left over from the development of the optic cup.
- Dual blood supply: the outer retina depends on the choriocapillaris, the inner retina on the central retinal artery.
- The fovea has cones only and gives the sharpest vision; the optic disc has no photoreceptors.
- Ganglion cell axons form the optic nerve.

## What it is

The retina is the neural tunic of the eye and, in fact, an outgrowth of the central nervous system. It is described in ten layers that alternate nuclei and synapses: light crosses almost its whole thickness before reaching the rods and cones, which sit on the outside next to the pigment epithelium. This layout explains retinal detachment, macular degeneration and diabetic retinopathy.

## Structure

- On H&E you see three bands of nuclei (outer nuclear, inner nuclear and ganglion cell layers) separated by two pale plexiform layers, where the synapses are.
- Direct signal path: photoreceptor → bipolar cell → ganglion cell; horizontal and amacrine cells make the side connections.
- Müller cells are the glia that span the full thickness; their processes form the outer and inner limiting membranes.
- Fovea: a central pit with cones only, where the inner layers are pushed aside; the site of sharpest vision.
- Optic disc: the exit of the ganglion cell axons; it has no photoreceptors (the blind spot).

## Function

- Pigment epithelium: engulfs the discs shed by the outer segments, recycles retinal (from vitamin A), absorbs stray light and forms the outer blood-retina barrier.
- Rods: contain rhodopsin, are very sensitive in dim light and do not see colour.
- Cones: three types of opsin for colour vision; they need brighter light and are concentrated in the macula.

## The ten layers of the retina (outer to inner)

| Layer | What it holds |
| --- | --- |
| 1. Pigment epithelium | Simple cuboidal epithelium with melanin, attached to Bruch's membrane |
| 2. Photoreceptor layer | Outer and inner segments of rods and cones |
| 3. Outer limiting membrane | Junctions between Müller cells and photoreceptors |
| 4. Outer nuclear layer | Nuclei of rods and cones |
| 5. Outer plexiform layer | Synapses of photoreceptors with bipolar and horizontal cells |
| 6. Inner nuclear layer | Nuclei of bipolar, horizontal, amacrine and Müller cells |
| 7. Inner plexiform layer | Synapses of bipolar and amacrine cells with ganglion cells |
| 8. Ganglion cell layer | Cell bodies of the ganglion cells |
| 9. Nerve fibre layer | Ganglion cell axons running to the optic disc |
| 10. Inner limiting membrane | Basal lamina of the Müller cells, facing the vitreous |

## Clinical notes

- Age-related macular degeneration: drusen build up between the pigment epithelium and Bruch's membrane; in the wet form new vessels grow in from the choroid.
- Diabetic retinopathy: capillary pericytes are lost, microaneurysms form and, later, fragile new vessels grow.
- Once separated from the pigment epithelium, photoreceptors lose their metabolic support; that is why retinal detachment is an emergency.

## Memory aid

The retina is «inside out»: light comes in through the fibre layer and crosses the whole retina to reach photoreceptors that have their backs against the pigment.

## Test yourself

Think of the answer, then tap the question to see it.

## Which nuclei make up the outer nuclear layer of the retina?

The nuclei of the photoreceptors, that is, the rods and cones.

## Between which layers does the retina split in a detachment?

Between the neural retina (photoreceptor layer) and the pigment epithelium.

## Why is the optic disc the blind spot?

Ganglion cell axons leave the eye there and there are no photoreceptors.

## Which glial cell spans the full thickness of the retina and forms its limiting membranes?

The Müller cell.

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## See it in 3D

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

- [Retina](https://durgical.com/en/anatomy/retina/)

## Related

- [The eye wall: cornea, sclera, uvea and lens](https://durgical.com/en/histology/the-eye-wall-cornea-sclera-uvea-and-lens/)
- [The neuron and synapse](https://durgical.com/en/histology/the-neuron-and-synapse/)
- [Glial cells: astrocytes, oligodendrocytes, microglia, Schwann cells](https://durgical.com/en/histology/glial-cells-astrocytes-oligodendrocytes-microglia-schwann-cells/)
- [Gray and white matter, cerebellar cortex, meninges](https://durgical.com/en/histology/gray-and-white-matter-cerebellar-cortex-meninges/)

## Related conditions

- [Retinal detachment](https://durgical.com/en/conditions/retinal-detachment/)
- [Age-related macular degeneration](https://durgical.com/en/conditions/age-related-macular-degeneration/)
- [Diabetic retinopathy](https://durgical.com/en/conditions/diabetic-retinopathy/)

[← 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: [14.1 Sensory Perception](https://openstax.org/books/anatomy-and-physiology-2e/pages/14-1-sensory-perception) (OpenStax, Anatomy and Physiology 2e, 2022); [How the Eyes Work](https://www.nei.nih.gov/learn-about-eye-health/healthy-vision/how-eyes-work) (National Eye Institute (NIH), 2026); [Retinal Detachment](https://www.nei.nih.gov/learn-about-eye-health/eye-conditions-and-diseases/retinal-detachment) (National Eye Institute (NIH), 2026).

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Representative model, for educational purposes only.

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Source: https://durgical.com/en/histology/retina-the-ten-layers-rods-and-cones/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/histology/retina-the-ten-layers-rods-and-cones/