Expression pattern of Dll4 during chick embryogenesis.

Notch and Delta signaling regulates cell-fate decisions in a variety of tissues in diverse organisms through cell-to-cell interactions. In this study we isolated a 696 bp fragment of chick Delta-like 4 (Dll4) cDNA and analyzed its expression pattern during chick development by in situ hybridization. We report a detailed description of cDll4 expression from HH-stage 8-30. Expression is seen in extraembryonic tissues and in the dorsal aorta throughout development but is absent from venules. Dll4 is expressed in the embryonic blood vessels, heart, somites, neural tube, limb, pharyngeal arches, esophagus, and in the developing eye. In accordance with the report from mice, cDll4 is a marker of the arterial type of endothelial cells. These analyses show that Dll4 is expressed in a wide range of tissues and organs suggesting its role in vascular development during chick embryogenesis.