Axial skeleton and pituitary gland in human fetuses with spina bifida and cranial encephalocele.

The purpose of this study was to investigate the axial skeleton and the pituitary gland in fetuses with spina bifida or cranial encephalocele in order to elucidate the pathogenesis of the conditions. The findings were related to former investigations performed on normal fetuses and on fetuses with anencephaly and rachischisis. Eight human fetuses from spontaneous or therapeutic abortions, 11-28 weeks of gestational age, were investigated. Radiographs were taken of the axial skeleton and histological investigation, including immunohistochemical marking for thyroid-stimulating hormone was performed on tissue blocks of the cranial base, including the sella turcica and the pituitary gland. Radiography revealed only minor malformations in the axial skeleton and not in all cases. The types of malformations resembled those seen in anencephaly and rachischisis. Histological investigations revealed severe malformations in the sella turcica region in spina bifida and minor ones in cranial encephalocele. Pharyngeally located adenopituitary gland tissue occurred in all fetuses. Anencephaly and cranial encephalocele seemingly are conditions resulting from different expressivity of the same multifactorial process of maldevelopment involving mesoderm (skeleton), neurectoderm (spinal cord and brain), and surface ectoderm (adenopituitary gland tissue). It is suggested that the molecular biological signaling between the notochord, the scleroderm, and the surface ectoderm is disturbed in spina bifida and cranial encephalocele.