Medicine, 17nivnit'er.uity of Illinoix, Chicago, Illinois FOUR FIGURESGrowth of the bones of the face owxrs in three ways, namely, replacement of cartilage by bonc (eridochondral growth), appositional growth on the surfaces (subperiosteal), and sutural growth. The purpose of this experiment was to study the nature of sutural growth and thc effects of injury upon it. I n a previous report (Selman and Sarnat, '55) it was shown that in the 42-day-old rabbit the region of the frontonasal suture was an active site of bone gromt,h. Therefore, this region was selected to study thc effects of trauma. The maximal injury was imposed, that of extirpation of the suture. MATERIAL A S D METHODS AnimnEs.In this study 49 (28 exprrimental and 21 control) growing fcmale New Zealand albino rabbits were used. Their ages ranged from 42 to 84 days at the time of the surgical operation. Rabbits w e w selected primarily bcctruse of the rapid rate of growth in the region of the frontonasal suture. 273 ABBE J. SELMAN AND UEKXABD G . SARRATThus, one would expect conditions affecting growth at this suture to be reflected in altered growth of the snout. Moreover, the snout readily lends itself to the placement of metallic implants and accurate serial roentgenography. However, the size and complexity of the pinna make difficult the insertion of earposts for serial roentgenography. The animals were fed ad libiturn on standard rabbit ration.The animals were anesthetized by injection into the marginal ear vein of a 1% aqueous solution of pentobarbital sodium (40 mg& body weight). To each dose, 0.25mg of atropine sulfate was added. Extirpation of the frontonasal suture, insertion of the radiopaque metallic implants and serial ceplralomctric roentgenography were then done.Eztirpation of frowtomasal sziture. The anesthetized animal WBS strapped prone on the operating board. The skin of the dorsum of the snout was clipped of hair, cleansed with 7070 ethyl alcohol and isolated with sterile towels. An aseptic technique mas observed throughout the surgical procedure. The skin and subcutaneous tissues were incised longitudinally in the midline from the region of the coronal suture to the nasal cartilage. After the wound margins were retracted, the periosteum was incised, elevated from the bone and rctractcd, and the frontonasal, interfrontal and internasal SIItures were exposed ( fig. la).

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