1. a group of photoreceptor cells in the compound eye of arthropods that forms a single optical unit
Usage: biology; entomology

Examples

• Each retinula in the dragonfly’s compound eye contains several photoreceptor cells.
• The retinula cells are arranged in a precise pattern within each ommatidium.
• Researchers studied how light is processed by individual retinula units.
• The compound eye consists of thousands of retinula clusters working together.
• Damage to the retinula can impair an insect’s ability to detect movement.
• Each retinula responds to light from a specific direction in the visual field.