Fetal Jaw Movement Affects Condylar Cartilage Development

Abstract

Using a mouse exo utero system to examine the effects of fetal jaw movement on the development of condylar cartilage, we assessed the effects of restraint of the animals' mouths from opening, by suture, at embryonic day (E)15.5. We hypothesized that pre-natal jaw movement is an important mechanical factor in endochondral bone formation of the mandibular condyle. Condylar cartilage was reduced in size, and the bone-cartilage margin was ill-defined in the sutured group at E18.5. Volume, total number of cells, and number of 5-bromo-2'-deoxyuridine-positive cells in the mesenchymal zone were lower in the sutured group than in the non-sutured group at E16.5 and E18.5. Hypertrophic chondrocytes were larger, whereas fewer apoptotic chondrocytes and osteoclasts were observed in the hypertrophic zone in the sutured group at E18.5. Analysis of our data revealed that restricted fetal TMJ movement influences the process of endochondral bone formation of condylar cartilage.

Mathematical Analysis of Mandibular Morphogenesis by Micro‐CT‐Based Mouse and Alizarin Red S‐Stained‐Based Human Studies During Development

“…After the operation, the fetuses together with the uterus were placed back in the abdominal cavity of the dam, and the incision on the abdominal muscle was sutured closed with 3-or 4-0 silk line; incision of the abdominal skin was closed by autosuture (MikRon 9 mm Autoclip Applier), and were allowed to develop exo utero till E18.5. As in our several previous studies (Hatta et al, 1994(Hatta et al, , 2002(Hatta et al, , 2004Habib et al, 2005Habib et al, , 2007Jahan et al, 2010), we observed that the exo utero surgery as described caused no general growth retardation, and neither the CRL, BW, nor the mandibular morphology of the E18.5 sham-operated fetuses were significantly different from those of the E18.5 in utero normal fetuses. Therefore, we here show only the results of sham-operated fetuses, and not those of in utero normal fetuses, as the control.…”

“…Prenatal TMJ movement restriction using the exo utero development system (Habib et al, 2005(Habib et al, , 2007Jahan et al, 2010) is a very strong form of mechanical stimulation to produce disharmony in the development of the mandible. This restriction of jaw movement clearly led to the morphological deformation of the mandible in the E18.5 sutured fetuses, and morphometric analysis in particular revealed a significant increase in the PD in the sutured group.…”

“…Exo utero surgery was performed as described previously (Hatta et al, 1994(Hatta et al, , 2002(Hatta et al, , 2004Habib et al, 2005Habib et al, , 2007Udagawa et al, 2006;Yamada et al, 2008;Jahan et al, 2010). Briefly, at E15.5, the pregnant dams were anesthetized with 50 mg/kg BW of pentobarbital.…”

“…Right panel: schematic representation of restrained jaw movement of mouse fetuses. Arrows indicate the suture fixation with 8-0 nylon (originally from Habib et al, 2005). B-E: Alizarin red Sstained human fetal mandibles [B (CRL 97 mm), C (CRL 121 mm), D (CRL 146 mm), and E (CRL 178 mm)].…”

Endoplasmic Reticulum Stress Regulates Rat Mandibular Cartilage Thinning under Compressive Mechanical Stress

“…1B). This regionalization method has been extensively used in studies on mandibular condylar cartilage (12)(13)(14)(15). The thickness of each zone was measured with Image-Pro Plus software.…”