title: Analysis of nephric duct specification in the avian embryo.
abstract: Vertebrate kidney tissue exhibits variable morphology that in general increases in complexity when moving from anterior to posterior along the body axis. The nephric duct, a simple unbranched epithelial tube, is derived in the avian embryo from a rudiment located in the anterior intermediate mesoderm (IM) adjacent to somites 8 to 10. Using quail-chick chimeric embryos, the current study finds that competence to form nephric duct is fixed when IM precursor cells are still located in the primitive streak, significantly before the onset of duct differentiation. In the primitive streak, expression of the gene HoxB4 is associated with prospective duct IM, whereas expression of the more posterior Hox gene HoxA6 is associated with more posterior, non-duct-forming IM. Misexpression of HoxA6, but not of HoxB4, in prospective duct-forming regions of the IM resulted in repression of duct formation, suggesting a mechanism for the restriction of duct formation to the anterior-most IM. The results are discussed with respect to their implications for anterior-posterior patterning of kidney tissue and of mesoderm in general, and for the loss of duct-forming ability in more posterior regions of the IM that has occurred during vertebrate evolution.
authors.affiliation: Department of Anatomy and Cell Biology, Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel.
authors.forename: Lital
authors.initials: L
authors.lastname: Attia
authors.forename: Ronit
authors.initials: R
authors.lastname: Yelin
authors.forename: Thomas M
authors.initials: TM
authors.lastname: Schultheiss
mesh_terms: D000818:Animals; D019521:Body Patterning / Q000235:genetics; D002454:Cell Differentiation; D002642:Chick Embryo; D002645:Chickens; D002678:Chimera; D005801:Genes, Homeobox; D018398:Homeodomain Proteins / Q000096:biosynthesis* / Q000235:genetics; D007668:Kidney / Q000196:embryology*; D008648:Mesoderm / Q000378:metabolism; D009399:Nephrons / Q000196:embryology*; D054240:Primitive Streak / Q000378:metabolism; D011784:Quail / Q000196:embryology; D015398:Signal Transduction; D014157:Transcription Factors / Q000096:biosynthesis* / Q000235:genetics
chemical_list: D018398:Homeodomain Proteins; D014157:Transcription Factors