title: Association between the development of the body axis and the craniofacial skeleton studied by immunohistochemical analyses using collagen II, Pax9, Pax1, and Noggin antibodies.
abstract: METHODS
  Immunohistochemical analyses on the axial skeleton from wild type mice.
  
  
  OBJECTIVE
  In the clinic, we have previously observed cervical spine defects associated with deviations in the posterior part of the occipital bone and with morphologic and functional variations in the craniofacial skeleton. As examples, cervical spine fusions occurred frequently in patients with mandibular overjet and even more frequently and more caudally in the cervical spine in patients with sleep apnoea. The aims of the present study were to elucidate this association between the spine and the cranium by comparing gene expression domains of important developmental genes known to be involved in vertebral column formation with gene expression in the craniofacial region.
  
  
  BACKGROUND
  This is the first study looking specifically on gene expression in the basilar part of the occipital bone that is formed around the cranial part of the notochord, thus connecting the spine and the craniofacial skeleton.
  
  
  METHODS
  The material consisted of 4 mouse embryos p.c. day 13.5, NMRI wild-type mice, from the same litter. The body axis, the cranial base, and the craniofacial area were studied by immunohistochemical analyses using Collagen II, Pax9, Pax1, and Noggin antibodies.
  
  
  RESULTS
  Pax1 expression was highly similar in the posterior part of the occipital bone and in the vertebral column, indicating that the basilar part of the occipital bone from a developmental standpoint can be considered the uppermost vertebra. Pax9 and Noggin expression domains were in accordance with those described previously.
  
  
  CONCLUSIONS
  The present study supports that the basilar part of the occipital bone may be regulated by similar developmental mechanisms as the vertebral column and may thus be regarded the uppermost vertebra. Thus, the clinically observed association between the cervical column and the craniofacial area has been proved by immunohistochemical methods.
authors.affiliation: Department of Orthodontics, Institute of Odontology, Wilhelm Johannsen Centre for Functional Genome Research, University of Copenhagen, Copenhagen, Denmark. LLS@odont.ku.dk
authors.forename: Liselotte
authors.initials: L
authors.lastname: Sonnesen
authors.forename: Dorrit
authors.initials: D
authors.lastname: Nolting
authors.forename: Klaus Wilbrandt
authors.initials: KW
authors.lastname: Kjaer
authors.forename: Inger
authors.initials: I
authors.lastname: Kjaer
mesh_terms: D000818:Animals; D019521:Body Patterning; D002352:Carrier Proteins / Q000494:pharmacology; D002574:Cervical Vertebrae / Q000196:embryology*; D024043:Collagen Type II / Q000494:pharmacology* / Q000502:physiology*; D005147:Facial Bones / Q000196:embryology*; D007150:Immunohistochemistry / Q000379:methods*; D051379:Mice; D009777:Occipital Bone / Q000196:embryology*; D051764:PAX9 Transcription Factor / Q000494:pharmacology; D051761:Paired Box Transcription Factors / Q000494:pharmacology; D000099176:Noggin Protein
chemical_list: D002352:Carrier Proteins; D024043:Collagen Type II; D051764:PAX9 Transcription Factor; D051761:Paired Box Transcription Factors; D000099176:Noggin Protein; C070835:PAX1 transcription factor