Pax6 expression patterns in Lampetra fluviatilis and Scyliorhinus canicula embryos suggest highly conserved roles in the early regionalization of the vertebrate brain.

We report expression patterns of the Pax6 gene in the dogfish Scyliorhinus canicula and the lamprey Lampetra fluviatilis during neurulation and at the beginning of organogenesis. At the stages studied, both genes display very similar expression domains in the dorsal forebrain, with a sharp posterior boundary at the diencephalon-mesencephalon border, in the hindbrain, excluding the floor plate and the roof plate, and in the spinal cord. The comparison of these expression patterns with those reported in osteichthyans suggests that the roles played by Pax6 in early brain regionalization have been highly conserved during vertebrate evolution.