Midline maxillofacial skeleton in human anencephalic fetuses.

The purpose of this study was to describe the midline maxillofacial skeleton (the axial skeleton anterior to the sella turcica) in 15 human anencephalic fetuses (14-19 weeks of gestation) by radiography and histology, and to relate the findings to skeletal patterns in the remaining part of the axial skeleton. Four patterns in the maxillofacial skeleton were recognized: normal structures, slightly deformed (6 cases); cleft palate (3 cases); incomplete nasal septum (3 cases); multilocular ethmoid cartilage (3 cases). No association was found between skeletal patterns in the different parts of the axial skeleton. The study demonstrates the existence of a developmental borderline in the anencephalic axial skeleton in the region of the sella turcica. It is presumed that this borderline indicates the boundary between skeletal tissue developed around the notochord (posterior axial skeleton) and the anterior skeletal components derived from neural crest cells.