| Abstract: | Growth of the craniofacial structures in the rat was studied with a vital-staining technique. The study was designed to determine the amount and direction of growth in the midsagittal region. A group of 44 male Long Evans rats weighing 90 gm ± 5 gm were given intraperitoneal injections of bone-marking agents. These injections consisted of terramycin, alizarin red S, trypan blue, and terramycin, plus alizarin red S, at 0, 3, 15 and 36 days after attainment of the standard starting weight. Cephalometric radiographs were made at the time of each injection. The rats were sacrificed at 66 days. Serial undecalcified sections were cut in the midsagittal plane at 80 μ. Certain anatomical landmarks were located on each section, coordinated, and plotted; a calibrated microscope stage and graduated eyepice were used. Specific areas of interest were photographed in color, with single-frame exposures, on 16 mm moving film. The specific growth sites were then analyzed on a Vanguard Motion Analyzer by measuring the separation of the individual bone marks. |
