Skull morphology and histology in the heterozygous offspring
of a transgenic founder mouse Del1, harbouring 6 copies of deletion
mutation in Col2a1 gene, were compared with those in normal siblings.
On visual observation and roentgenocephalometric examination the heads
of heterozygous Del1 mice were smaller than normal. Histologically the
sizes of cartilaginous structures of the cranial base were reduced.
Severe defects were seen in the temporomandibular joint as progressive
osteoarthritic lesions. These observations elucidate the relationship
between the genotype and phenotype and demonstrate that heterozygous
Del1 mice are a useful model for studies on a genetic disturbance
where ‘clinical’ manifestations are not evident until
adult age.