Pax7 expression in the adult rat superior colliculus following optic nerve injury.

The transcription factor Pax7 has been implicated in the normal development of the superior colliculus and continues to be expressed in the adult superior colliculus, where it is concentrated in the retino-recipient laminae. Here we assessed, immunohistochemically, Pax7 expression in the adult rat superior colliculus after unilateral intraorbital optic nerve transection. We show that after optic nerve transection, the number of Pax7-expressing cells increased to re-establish the developmental rostral-caudal gradient and that these Pax7-expressing superior colliculus cells were neurons. These findings may have implications for the design of therapeutic interventions to restore functional connections in the adult visual pathway.