i mean the photoreceptors have axon and dendrite and body cell or it is not neuron any more . can we say outer segment of photoreceptor cell is dendrite ? of course these have body cells but i am not sure they are neuron or not


1 Answer 1


Photoreceptors are considered neural based on embryonic origin: they derive from neuroepithelial cells like neurons do.

Neuroepithelial cells also produce non-neuronal cells like some glial cells.

It doesn't make much sense to worry too much about whether a rod/cone photoreceptor is a neuron or not. They don't have long axons or dendrites, but they need not have either to be called a neuron. They make synapses, but these synapses are highly specialized and different from other types of neurons; that isn't sufficient to not call them a neuron. They don't fire action potentials, but they need not fire action potentials to be called a neuron. They do release neurotransmitter, but there are other cells that also release neurotransmitters that are not considered neurons. Ultimately, deciding whether a cell is a neuron or not is a matter of semantics, not biology.

Most texts I am familiar with consider them neurons because of their neural origin, which differentiates them from other sensory cells that derive from other tissue.


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