Fgf-R3 is expressed in a subset of chicken spinal motorneurons.

The expression pattern of the fibroblast growth factor receptor Fgf-R1, R2 and R3 genes was studied in the chicken spinal cord using in situ hybridization (ISH). Unlike Fgf-R1 which is widely expressed in motoneurons, Fgf-R3 is expressed in a subset of motoneurons in the medial subdivision of the median motor column (MMCm) that also express Islet-1 and Lim-3. The motoneuron identity of the labelled cells was confirmed by double ISH and by single cell RT-PCR. Interestingly, E3.5 spinal cord motoneurons do not express Fgf-R3, suggesting the expression of Fgf-R3 in motoneurons begins with axonal growth.