Width of the Craniofacial Complex During Formation of the Secondary Palate

Abstract

Attempts to elucidate the formation of the secondary palate have in— volved extensive use of teratological methods. To date there have been few cephalometric studies of the growth of the fetal craniofacial complex aimed at a better understanding of the interrelationship of various growth parameters during closure of the secondary palate. Zeiler, VVeinstein, and Gibson (18) found a differential growth spurt of the mandible, relative to the maxilla, prior to and during palatal closure in the rat, which was also observed in mice by Hart, Smiley, and Dixon ('7). Increase in length of the mandible per 83 was essentially linear during shelf movement and the vertical dimension, which is an indicator of mandibular position and the degree of cranial base extension, may be more significant than mandibular length as a prerequisite for palatal shelf movement (7). Studies by Har— ris (5, 6) using mixed species and strains of rodents, as well as cortisone-treated mice, revealed that the degree of cranial base flexion could restrict palatal movement at the critical time for palatal closure. In another growth study, Deuschle and Kalter (3) reported that the mandibles of neonatal mice with cortisone—induced clefts of the palate were larger than those of the normal offspring, while Schwartz and Chaudhry (11) observed shorter mandibles in similar experimental animals. Linear and angular measurements of the length and height of the cra-niofacial complex during closure of the secondary palate have seldom been examined and there have been no detailed metrical studies on craniofacial width. The purpose of the present investigation was to carry out a quantitative appraisal of maxillary arch width, nasal septal height and septal width prior to, during and after closure of the secondary palate. Methods Mice of the A/Jax strain, which produce spontaneous clefts of the lip and palate, were bred on Monday and Friday from 9:00 am. to 12 noon. The authors are affiliated with the