Bernard G. Sarnat

Growth pattern of the mandible: some reflections.

The dynamics of the growth of bones is a complex process. The growth pattern of the mandible has been assessed by the application of various methods described for the study of the growth of bones. Some of these lend themselves primarily to basic experimental rather than clinical work. The use of any one of these methods will reveal certain information. With the use of two or more of them in combination, however, considerably more accurate information can be obtained. Since John Hunters classical descriptions more than 200 years ago, advances in the understanding of the growth pattern of the mandible have been possible with the refinement of older methods and the development of newer ones. To date, serial cephalometric roentgenography in concert with radiopaque implants, which serve as fixed reliable markers, is the most accurate method to determine the growth pattern of the mandible. To this armamentarium, digital subtraction radiography, computerized tomography, and magnetic resonance imaging may be methods that will offer more detailed and accurate information.

Regional Variations in Chondrocyte Proliferation in the Cartilaginous Nasal Septum of the Growing Rabbit

Experimental resection of cartilaginous nasal septuin in the growing rabbit results in a greatly undderdeveloped snout, relative mandibular prognathism, and malocclusion and overeruption of the incisors (B.G. SARNNAT and M.R. WEXLER, Amer I Anat, 118:755-768, 1966). Preliminary autoradiographic studies with tritiated thymidine were undertaken to determine normal levels of proliferative activity in the young rabbit cartilaginous nasal septum. A review of the literature revealed no similar study. A 3-week-old Dutch rabbit* was given a single intraperitoneal injection of 2598gc of tritiated thymnidine and killed one hour later. The head was divided parasagittally and fixed in Hollandes modification of Bouins fluid. The cartilaginous nasal septum region was embedded in paraffin. Parasagittal sections were cut 6[t thick and were autoradiographed with an emulsiont in accordance wx ith the method of Messier and Leblond (Proc Soc Exp Biol 96:7-1