THE ADENOHYPOPHYSIS AND THE CRANIAL BASE IN EARLY HUMAN-DEVELOPMENT

The purpose of the present study is to chart the normal human developm ent of the denohypophyseal part of the pituitary gland and of the cran ial base, with special attention given to the possible presence of pha ryngeal remnants of adenohypophyseal tissue. From 31 human embryos and fetuses (7-21 weeks of gestation) midsagittal, paraffin-embedded tiss ue blocks of the cranial base, including the pituitary gland and the p haryngeal wall, were investigated histologically. The identification o f adenohypophyseal tissue included immunohistochemical methods. In ear ly stages, the adenohypophysis of the pituitary gland is connected to the pharyngeal epithelium through the lining of Rathkell's pouch, from which it originates. The cartilaginous cranial base is laid down post eriorly to the gland region. The notochord is recognizable within this cartilaginous tissue as a continuous wave-shaped structure that disap pears when the cartilage begins to proliferate rostrally beneath the p ituitary gland. From this stage in development adenohypophyseal tissue is not demonstrated pharyngeally. The cartilaginous cranial base is v isible in its full antero-posterior extent before ossification starts. Cranio-pharyngeal canals are not registered in the cranial base. This study intends to define a standard for subsequent autopsy description s of the pituitary gland region in craniofacial malformations.