Wnt receptors and Wnt inhibitors are expressed in gradients in the developing telencephalon

The caudomedial margin of the medial pallium, known as the cortical hem, expresses several Wnt genes that have been shown to be crucial for cortical development. We examined the expression of members of the Frizzled (mFz) family of Wnt receptors and the Secreted Frizzled Related Protein (SFRP) family of Wnt inhibitors during telencephalic development. We found that mFz-5 and mFz-8 are specifically expressed in the neocortical neuroepithelium and excluded from the hippocampal neuroepithelium in early telencephalic development, whereas mFz-9 and mFz-10 have expression domains confined to the medial pallium. In addition, SFRP-1 and SFRP-3 are expressed in opposing anterolateral to caudomedial gradients within the telencephalic ventricular zone throughout corticogenesis.