Invagination of Human Palatal Epithelium Prior to Contact

Abstract

Bergengriin (2) and Peter (.9) were among the first investigators to examine the midline palatal epithelium and to draw attention to the persistence of epithelial remnants after its breakdown. A recent theory of cleft palate formation implicated the occurrence of epithelial pearls or epithelial remnants in the palatal shelves of human abortuses with cleft palates (4). Epithelial pearls were thought to indicate the original site of fusion of the two palatal shelves, and it was presumed from this evidence that most cleft palates in man resulted from post—fusion rupture. This theory was perpetuated by Kraus (5) on the basis of similar evidence. He proposed that viral infections or anti—organ antibody reactions could cause degeneration of palatal tissue, and combined with the rapid increase in'breadth of the face, rupture of the palate would result. Most of the histological investigations on palatal development have been concerned primarily with the breakdown of the midline palatal epi-thelium. Recently, Mato, Aikawa and Katahira (7) and Mato, Smiley and Dixon (8) discussed epithelial changes in the presumptive regions of nasal and palatal fusion of human fetuses at the light and electron micro— scope levels. Their results emphasized that the cellular changes which were observed, including epithelial cell degeneration and disarrangement, appeared prior to contact of palatal processes and nasal septum. The present investigation presents new findings on the possible method of formation of epithelial pearls in the presumptive areas of palatal fusion in human fetuses. Materials and Methods Human fetuses from therapeutic abortions, of approximately 9 weeks menstrual age, were fixed in 10% formalin solution for two days. The Dr. M.