Constitutive expression of FGF4 disrupts the development of the eye and the anterior CNS during mouse embryogenesis, but does not influence the expression of shh in these areas

The biological consequences of constitutive fibroblast growth factor-4 (fgf4) expression have been analysed during anterior CNS development of mouse chimeric embryos. Severe mutant embryos exhibit exencephaly, absence of eye development and anomalous differentiation of the euroepithelium. These embryos also show ectopic limb buds resembling the early phases of limb development. Because our results show that anterior CNS in those chimeric embryos does not express shh ectopically, we suggest that malfor- mations may be due to interference between the ectopic expression of fgf4 in the cephalic area and the receptors for the members of the FGF family that regulate brain and eye development, namely fgf8. If this is correct, the results indirectly support the crucial role of fgf8 in patterning the anterior CNS.