Tbx5 and the retinotectum projection

Dorsal and ventral aspects of the eye are distinct from the early stages of development. The developing eye cup grows dorsally, and the choroidal fiss ure is formed on its ventral side. Retinal axone from the dorsal and ventra l retina project to the ventral and dorsal tectum, respectively. Misexpress ion of the Tbx5 gene induced dorsalization of the ventral side of the eye a nd altered projections of retinal ganglion cell axons. Thus, Tbx5 is involv ed in eye morphogenesis and is a topographic determinant of the visual proj ections between retina and tectum.