Mouse Genome Informatics
ht
    Pax9tm1Hpt/Pax9tm1Rbal
involves: 129 * C57BL/6 * CD-1
Key:
phenotype observed in females
phenotype observed in males
N normal phenotype
mortality/aging
• underrepresented at weaning

craniofacial
• at E13.5 the size of the mesenchymal cell condensations underlying the posterior part of the dental lamina is reduced, but the dental papilla of the first molar has formed
• in the upper incisors ameloblasts are present at 2 months of age but absent by 5 months
• in the upper incisors ameloblasts fail to elongate and produce only a thin layer of pre-enamel
• at P0 all third molars are arrested prior to the bud stage and the lower second molars are arrested at the bud stage
• at P0 the lower first molars have reached the bell stage but lack polarization and alignment of the ameloblasts and odontoblasts
• at P0 the upper first and second molars are mostly growth retarded
• all mice lack lower incisors
• the lower first molars show significant attrition and formation of reparative dentin
• the upper third and lower second and third molars are unilaterally or bilaterally absent
• lower third molars and incisors fail to erupt and other teeth in the lower jaw may also fail to erupt
• irregular dentin formation is indicated by the presence of 'contour lines of Owen'
• the upper incisors lack enamel; however enamel formation in the molars is normal
• more severe tooth loss than in Pax9tm1Hpt homozygotes with all mice lacking at least 4 teeth (oligodontia) and some lacking all lower teeth

growth/size/body
• at E13.5 the size of the mesenchymal cell condensations underlying the posterior part of the dental lamina is reduced, but the dental papilla of the first molar has formed
• in the upper incisors ameloblasts are present at 2 months of age but absent by 5 months
• in the upper incisors ameloblasts fail to elongate and produce only a thin layer of pre-enamel
• at P0 all third molars are arrested prior to the bud stage and the lower second molars are arrested at the bud stage
• at P0 the lower first molars have reached the bell stage but lack polarization and alignment of the ameloblasts and odontoblasts
• at P0 the upper first and second molars are mostly growth retarded
• all mice lack lower incisors
• the lower first molars show significant attrition and formation of reparative dentin
• the upper third and lower second and third molars are unilaterally or bilaterally absent
• lower third molars and incisors fail to erupt and other teeth in the lower jaw may also fail to erupt
• irregular dentin formation is indicated by the presence of 'contour lines of Owen'
• the upper incisors lack enamel; however enamel formation in the molars is normal
• more severe tooth loss than in Pax9tm1Hpt homozygotes with all mice lacking at least 4 teeth (oligodontia) and some lacking all lower teeth

endocrine/exocrine glands
N
• thymus morphology is normal and no signs of defective parathyroid or ultimobranchial body function (as shown by normal calcium and phosphate homeostasis) are seen

Mouse Models of Human Disease
OMIM IDRef(s)
Tooth Agenesis, Selective, 3; STHAG3 604625 J:104121