Avian pelvis originates from lateral plate mesoderm and its development requires signals from both ectoderm and paraxial mesoderm.
The pelvic girdle is composed of three skeletal elements: ilium, pubis, and ischium. In comparison with other parts of the postcranial skeleton, its development is not well known to date. To elucidate the embryonic origin of the avian pelvic girdle and the signaling centers that control its development, we have performed extirpation and quail-to-chick grafting experiments. The results reveal that the entire pelvic girdle originates from the somatopleure at somite levels 26 to 35. No somitic cell contribution to skeletal elements of the pelvis has been detected. Removal of the surface ectoderm covering the lateral plate mesoderm has revealed that ectodermal signals control the development of the pelvic girdle, especially the formation of the pubis and ischium. The impaired development of the ischium and pubis correlates with the downregulation of Pax1 and Alx4, two transcription factors that control the normal development of the ischium and pubis. Although of somatopleural origin, the development of the ilium depends on somitic signals. Insertion of a barrier between somites and somatopleure disrupts the expression of Emx2 and prevents normal development of the ilium but does not affect the expression of Pax1 or Alx4 and the development of the pubis and ischium. Thus, the development of the ilium, but not of the pubis and ischium, depends on somitic and ectodermal signals.
Malashichev
Yegor
Y
Department of Vertebrate Zoology, Faculty of Biology and Soil Sciences, St Petersburg State University, Universitetskaya nab, St Petersburg, Russia. malashichev@gmail.com
Christ
Bodo
B
Pröls
Felicitas
F
D000818:Animals; D002642:Chick Embryo; D002645:Chickens; D003370:Coturnix; D004475:Ectoderm / Q000196:embryology* / Q000378:metabolism; D004625:Embryo, Nonmammalian / Q000196:embryology / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D018398:Homeodomain Proteins / Q000235:genetics; D007085:Ilium / Q000196:embryology / Q000378:metabolism; D007512:Ischium / Q000196:embryology / Q000378:metabolism; D018878:Limb Buds / Q000196:embryology / Q000378:metabolism; D008161:Lumbosacral Region / Q000601:surgery; D008648:Mesoderm / Q000196:embryology* / Q000378:metabolism / Q000637:transplantation; D051761:Paired Box Transcription Factors / Q000235:genetics; D010388:Pelvis / Q000196:embryology*; D011630:Pubic Bone / Q000196:embryology / Q000378:metabolism; D019170:Somites / Q000601:surgery / Q000637:transplantation; D016378:Tissue Transplantation / Q000379:methods; D014157:Transcription Factors / Q000235:genetics; D000099260:Empty Spiracles Homeobox Proteins
D018398:Homeodomain Proteins; D051761:Paired Box Transcription Factors; D014157:Transcription Factors; D000099260:Empty Spiracles Homeobox Proteins; C070835:PAX1 transcription factor