5′‐Nucleotidase immunoreactivity of perineuronal microglia responding to rat facial nerve axotomy

The ecto-enzyme 5'-nucleotidase was localized immunocytochemically in the axotomized rat facial nucleus. As revealed by the monoclonal antibody 5N4-2,5'-nucleotidase immunoreactivity markedly increased on perineuronal microglia during the first week following axotomy, and gradually disappeared from these cells by the end of the third post-operative week. Interestingly, parenchymal microglia were not or only weakly stained. These findings indicate that 5'-nucleotidase 5N4-2-immunoreactivity may serve as a marker for perineuronal microglia, a population of satellite glial cells that appear to be actively engaged in lesion-induced synaptic changes during regeneration.