Growth rate of the vomer in normal and cleft lip and palate human fetal specimens.

The present study, part of an ongoing investigation of normal and dysmorphic development of the human fetal oronasal capsule, examined the rate of growth of the vomer. For comparative purposes, 29 human fetal specimens (20 "normal" and 9 cleft lip and palate [CLP]) were celloidin embedded, sectioned, stained with hematoxylin and eosin, and serially digitized. The specimens ranged from 8 to 21 weeks in postmenstrual age. The application of a well-documented three-dimensional reconstruction technique provided quantification of several aspects of the vomer. CLP vomer length and volume were growing at a faster rate in the 8 to 21 week age range. Growth curves were produced by plotting length and volume against postmenstrual age and a significant difference was noted between the slopes (growth rate) of the linear component of the normal and CLP growth curves for vomer length (p less than .001) and volume (p less than .001). This study tested the hypothesis of a more rapidly growing 8 to 21 week CLP vomer and observed that the growth trends of the CLP vomer are similar to those of the CLP nasal septum, which also was found to possess a significantly larger (p less than .001) volumetric growth rate throughout the course of the vomer. Comparative findings suggest that a pathogenetic correlate of CLP is the rapid enlargement of the midline structures of the oral and nasal capsules.