THREE DIMENSIONAL MORPHOMETRIC STUDIES

Three Dimensional Morphometric Studies of the Articulating Surfaces of the Mandibular Condyle Among Inbred Strains of Mice

Three Dimensional Morphometric Studies of the Articulating Surfaces of the Mandibular Condyle Among Inbred Strains of Mice

Aims

Conduct a rigorous morphometric study using micro-computed tomographic (micro-CT) imaging to obtain 3-D architectural information of the articulating surfaces of the mandibular condyle in order to determine and quantify size and shape differences among and between different inbred strains.

Specific Aims

Quantify morphologic differences bilaterally of the articulating surfaces of the condyle and ramus of the mandible among mice of similar Strain (B6, C3H and F2).

Quantify morphologic differences in the articulating surfaces of the condyle and ramus of the mandible between 2 groups of mice B6, C3H and F2.

Determine which part of the microanatomy of the articulating surfaces of the condyle are more stable and less susceptible to morphologic changes

Determine which area of the ramus of the mandible are more stable and less susceptible to morphologic changes in mice of the same strain.

Significance of the Study

Primary and secondary cartilages differ in cellular organization, in pattern of growth and in some biochemical features such as the types ofcollagen.

Preliminary Studies

The mandibular condyle plays an important role in the development of the orofacial complex. The condylar cartilage acts as a regional adaptive growthsite. Condylar cartilage of the mandible differs from other cartilages such as the synchondroses, the nasal septal cartilage, the epiphyseal growth plates and the femoral head cartilage. The latter are all considered to be 'primary cartilages' while the condylar cartilage is defined as 'secondary cartilage'. These terms refer to the difference in embryonic origin; the primary cartilages appear earlier in the embryonic development than the secondary ones. Secondary cartilages are not derived from the primary cartilaginous skeleton, but they are mainly associated with membranous bones. In the mandible, secondary cartilages are found in the angular, condylar and coronoid processes.

Primary cartilage is supposed to have a relatively independent growth potential and to be less sensitive to functional factors whilecartilage of the mandibular condyle is considered highly adaptive to biomechanical forces. Mandibular condylar cartilage has long been the object of many investigations due to its apparent duality. Although it has been demonstrated that this cartilage is endowed with an adaptive remodelling potential, the mandibular condyle also possesses an intrinsic growth potential. However, the relative importance of the adaptive and intrinsic growth during development is always debated and the exact factors regulating growth of the mandibular condyle are still unclear.

Most of the knowledge on the regulation of cartilaginous growth is derived from studies on epiphyseal plates of long bones. Growth of long bones results from the proliferation and differentiation of chondrocytes in epiphyseal growth plates. Cartilage growth is partly epigenetically determined but is also influenced by extrinsic factors like mechanical stimuli and by systemic (hormones) and local mediators (growth factors and cytokines). Insulin-like growth factor-I (SPHARM-PDM) is a polypeptide of 70 amino acid residues, which stimulates cell proliferation, induces cell differentiation and stimulates differentiated functions in several cell ...