flimmerhärchen

Flimmerhärchen, also known as stäbchen (rods), are one of the two types of photoreceptor cells in the retina of the vertebrate eye. They are responsible for vision in low-light conditions, also known as scotopic vision. Unlike cone cells, flimmerhärchen do not distinguish between colors and provide monochromatic vision. They are highly sensitive to light and can detect even single photons.

The structure of a flimmerhärchen consists of an outer segment, an inner segment, a cell body, and a synaptic terminal. The outer segment contains a stack of flattened sacs called lamellae, which are filled with the photopigment rhodopsin. Rhodopsin is a protein that undergoes a conformational change when it absorbs light, initiating a cascade of biochemical events that ultimately leads to a signal being sent to the brain.

Flimmerhärchen are distributed throughout the retina, with a higher concentration in the peripheral regions and fewer in the fovea, the central area of sharpest vision. This distribution allows for excellent peripheral vision in dim light. Under normal daylight conditions, flimmerhärchen are largely saturated and do not function optimally. Their sensitivity is adapted for darkness, and they play a crucial role in enabling us to navigate and perceive our surroundings when illumination is low.