Differential responses to parathyroid hormone-related protein (PTHrP) deficiency in the various craniofacial cartilages

Abstract

PTHrP null mutant mice exhibit skeletal abnormalities both in the craniofacial region and limbs. In the growth plate cartilage of the null mutant, a diminished number of proliferating chondrocytes and accelerated chondrocytic differentiation are observed. In order to examine the effect of PTHrP deficiency on the craniofacial morphology and highlight the differential feature of the composing cartilages, we examined the various cartilages in the craniofacial region of neonatal PTHrP deficient mice. The major part of the cartilaginous anterior cranial base appeared to be normal in the homozygous PTHrP deficient mice. However, acceleration of chondrocytic differentiation and endochondral bone formation was observed in the posterior part of the anterior cranial base and in the cranial base synchondro-ses. Ectopic bone formation was observed in the soft tissue-running mid-portion of the Meckel's cartilage, where the cartilage degenerates and converts to ligament in the course of normal development. The zonal structure of the mandibular condylar cartilage was scarcely affected, but the whole condyle was reduced in size. These results suggest the effect of PTHrP deficiency varies widely between the craniofacial cartilages, according to the differential features of each cartilage. Anat Rec 255:452-457, 1999. 1999 Wiley-Liss, Inc.

Mandibular deformities in parathyroid hormone-related protein (PTHrP) deficient mice: possible involvement of masseter muscle

“…a-f ×30; g,h ×150 ossification occur in homozygous mice (Karaplis et al 1994;Amizuka et al 1994Amizuka et al , 1996a, and slight abnormalities occur in heterozygous mice (Amizuka et al 1996b). Recently, abnormalities of craniofacial cartilages in the cranial base, mandibular condyle and Meckel's cartilage were reported (Ishii-Suzuki et al 1999). From these studies, it is regarded as an inhibitory factor for chondrocyte differentiation.…”

“…In support of this, transgenic mice that overexpress PTHrP show delayed endochondral ossification . Recently, abnormalities of craniofacial cartilages in the cranial base, the mandibular condyle and Meckel's cartilage were reported (Ishii-Suzuki et al 1999). However, to date abnormalities have not been reported in bones that form via intramembranous ossification.…”

Developmental Regulation of the Growth Plate and Cranial Synchondrosis

“…3A). However, chondrocyte differentiation is markedly more accelerated in the ISS and SOS of PTHrP −/− mice, compared with the growth plate (Ishii-Suzuki et al 1999). This accelerated chondrocyte differentiation is associated with more accelerated endochondral bone formation.…”

Developmentally Regulated Expression of Msx1, Msx2 and Fgfs in the Developing Mouse Cranial Base

“…Deciphering cranial base development through a genetic approach has just started. [14][15][16][17][18] Studies on other structures, particularly the appendicular bones, provide some important clues for studies on the cranial base. In the present study, the author examined a set of genes that are important for craniofacial and skeletal development, including members of the Fgf family and Msx1 and Msx2.…”