HISTOMORPHOLOGIC ANALYSIS OF THE SOFT PALATE MUSCULATURE IN PRENATAL CLEFT AND NONCLEFT A JAX MICE/

The two specific aims of this study were as follows: to evaluate the a ppropriateness of the A/Jax mouse model in the investigation of the ke y cellular stages in prenatal soft palate morphogenesis and myogenesis ; and to describe structural differences in the histomorphology of the soft palate anatomy from cleft and noncleft mice prior to, during, an d after palatogenesis, Cleft-induced and control groups of A/Jax mouse embryos from timed pregnancies were harvested sequentially on gestati onal days 15 to 19, Embryos were weighed and staged for external body morphology. The heads were removed and fixed for light microscopy, sec tioned serially in the frontal plane at 10 mu and stained with hematox ylin-eosin to characterize and compare the soft palate musculature. Al l observations were made at the head depth of the trigeminal ganglion in both age- and stage-matched embryos. The following findings were ma de: (1) the A/Jax mouse is a suitable animal model for the study of so ft palate myogenesis; (2) there were no discernible morphologic differ ences between the soft palate muscles in cleft and noncleft A/Jax mice when viewed under light microscopy; (3) the soft palate and related m uscles were identifiable as muscle fields, in both the cleft and noncl eft fetuses, as early as gestational day 15 and as specific muscles at gestational day 18; (4) in both the cleft and noncleft A/Jax fetuses, the soft palate muscles appeared in a sequential anatomic fashion (th e palatine aponeurosis appeared first, next the tensor palatini, and t hen the levator palatini muscles); and (5) in the cleft palate fetuses , both pterygoid plates were angulated and displaced laterally.