Histological study of the nasal septal cartilage in BALB/c-bm/bm mouse which spontaneously induces malocclusion

The BALB/c-bm/bm mouse is characterized by short limbs and short tail attributed to undersulfated glycosaminoglycans. Anterior transverse crossbite sometimes spontaneously appears in BALB/c-bm/bm mice. The BALB/c-bm/bm mouse shows a short nose and cranium. The reason for hypo-growth of anterior craniofacial structures has not been clarified, although the nasal septal cartilage might be related to the growth of anterior craniofacial structures. Therefore, the purpose of this study was to evaluate histological findings of the nasal septal cartilage at the border region of the ethmoid and sphenoid bone in BALB/c-bm/bm mice.BALB/c mice (wild type) and BALB/c-bm/bm mice with normal occlusion (bm/bm) were used. Sagittal sections of female mice aged 2, 4, and 8 weeks were stained with hematoxylin and eosin for histological analysis.At the border region between the nasal septal cartilage and the ethmoid bone in bm/bm, the area of proliferative zone was significantly smaller than that in wild type. At the border regions between the nasal septal cartilage and both the ethmoid and sphenoid bones, the number of proliferative chondrocytes was significantly smaller. Normal endochondral ossification was not observed at the border region between the nasal septal cartilage and the sphenoid bone in bm/bm.The findings suggest that disorder of endochondral ossification in the nasal septal cartilage contributes to the hypo-growth of anterior craniofacial structures in bm/bm.