High frequency of ciliated neuropeptide Y-immunoreactive neurons in rat striatum.

An analysis of the ultrastructure of neuropeptide Y-immunoreactive neurons in rat striatum revealed the presence of a cilium in half of the neurons serially sectioned in part, and in a quarter of the neurons observed in single sections. It is speculated that the cilium is a developmental remnant, i.e., a sign of the less differentiated state of the NPY-containing neurons compared with the other neurons, and that this could explain the plasticity of this type of neuron after lesions.