Homo- or heteromers. At 9.5 dpc it is expressed in the nephric duct, the dorsal neural tube, the epithelia of the branchial arches, and the optic vesicle. In 14.5 dpc embryos, like in earlier ones, it is expressed in the dorsal spinal cord and the brain, where it is restricted to the proliferating ependymal and cortical cell layers. Expression is also detected in smooth muscles of the digestive tract as well as in the epithelia of the salivary gland, the inner ear, and the developing nephrons of kidney. In early embryos, it is expressed in the epithelium of the branchial arches. At 14.5 dpc, Emu1 is restricted to the epithelium in the advanced developing kidney (at 15.5 dpc and later), transcripts are detected in the epithelium of the developing nephrons and in the collecting duct epithelium. May be due to a competing acceptor splice site.