Late developmental expression of DARPP-32 in the chick optic tectum

Immunohistochemical techniques reveal that the dopamine- and cAMP-regulated phosphoprotein DARPP-32 is detectable in neurons of the chick optic tectum starting on embryonic day 13. The expression levels then increase steadily from embryonic day 15 through the first posthatching day. After 15 days posthatching, expression of DARPP-32 reaches the adult pattern, with many labeled cells in tectal layers 11 and 12. These cells exhibit a bipolar shape, with long processes directed both to the deep and superficial layers. These results suggest that DARPP-32 is present in specific neuronal populations of the chick tectum and that this protein may not have a function in early ontogenetic processes.