Expression of FGFR1, FGFR2 and FGFR3 during early neural development in the chick embryo

Studies involving chick embryos have implicated FGFs in neural induction an d patterning as well as in other developmental events. Detailed analyses of FGF receptor expression at early stages of neural development have not bee n reported for the chick embryo and are incomplete for other vertebrate cla sses. Here we show the expression patterns of three FGF receptors, (FGFR1, FGFR2 and FGFR3) in embryonic stages between gastrulation and limb bud form ation, focussing particularly on neural tissues. Between neural induction a nd neurulation, all three receptors are expressed in the neural plate albei t with distinct and overlapping distributions. During early neuromere forma tion FGFR1 transcripts are present throughout the neural tube, while transc ripts for FGFR2 and FGFR3 become restricted to regions of the diencephalon and spinal cord. A little later, FGFR2 and FGFR3 are additionally expressed in the anterior midbrain and within the hindbrain. During later neuromere development, FGFR1 transcripts become localised to the telencephalon, anter ior dorsal diencephalon and throughout the midbrain and hindbrain, whereas FGFR2 mRNA is restricted to dorsal telencephalon, dorsoanterior midbrain an d hindbrain. FGFR3 is also expressed in anterior midbrain and hindbrain dur ing this developmental period, and is additionally expressed in the posteri or telencephalon, in the pretectum, and at the zona limitans intrathalamica . The observed expression patterns of all three receptors within the hindbr ain, including rhombomere boundaries, are complex and dynamic. Expression p atterns within the somites, eye, head mesenchyme, branchial arches, limb bu ds, nephric kidney and pharynx are also described. (C) 2000 Elsevier Scienc e Ireland Ltd. All rights reserved.