FGF2 decreases the thickness of early born tectal layers.

<p>By ED12, birds treated with FGF2 showed a 50% decrease in the radial thickness of the deep layers in the lateral tectum compared to controls (A, B, D). In these same lateral areas, despite the presence of “volcano”-like disturbances in the outer laminae (B), there is no statistically significant difference in the thickness of the superficial or the middle layers between FGF2-treated birds and controls (D). The caudal, folded areas of FGF2 treated birds (C) exhibited no significant changes in the thickness of any layers (D).