Expression of the receptor tyrosine kinase gene EphB3 during early stages of chick embryo development.

The expression pattern of the receptor tyrosine kinase gene EphB3 was examined during the early stages of chick embryogenesis, and is described in this report. In the gastrula, EphB3 is expressed in epiblast cells adjacent to and entering the anterior portion of the primitive streak; expression is extinguished once cells have ingressed. At headfold stages, EphB3 is strongly transcribed in the floor of the foregut and in anterior lateral endoderm, and is expressed in the subjacent cardiogenic mesoderm. EphB3 is transiently expressed in the lateral ectoderm, neural tube, and neural crest during these stages. Later neural expression is localized to the mesencephalon. In the somitic mesoderm, EphB3 is initially expressed in the sclerotome, but later is expressed predominantly in the dermatome. Prominent expression is also detected in the developing heart, liver, posterior ventral limb bud mesenchyme, pharyngeal arches, and head mesenchyme.