{"type":"root","children":[{"type":"paragraph","children":[{"type":"text","value":"NeuN (Feminizing Locus on X-3, Fox-3, or Hexaribonucleotide Binding Protein-3) is a neuron-specific protein that is present in most Central Nervous System (CNS) and Peripheral Nervous System (PNS) neuronal cell types. NeuN protein distributions are restricted to neuronal nuclei, perikarya and some proximal neuronal processes in both fetal and adult brain. However, some neurons fail to be recognized by NeuN at all ages, such as INL retinal cells, Cajal-Retzius cells, Purkinje cells, inferior olivary and dentate nucleus neurons, and sympathetic ganglion cells. NeuN is widely used to label neurons since the vast majority of neurons are strongly positive. NeuN immunoreactivity becomes obvious as neurons mature, typically after they have downregulated expression of Doublecortin, a marker seen in the earliest stages of neuronal development."}]}]}