EARLY DEVELOPMENT OF THE HUMAN PHARYNGEAL HYPOPHYSIS — A PRELIMINARY REPORT1

Most textbooks of Embryology and of Histology generally agree on the following more or less well-known facts: (1) the hypophysis or pituitary gland occupies a depression (the hypophyseal fossa) within the sella turcica which is located on the cranial aspect of the body of the sphenoid bone; (2) the hypophysis is a composite organ consisting of two main portions, an anterior and a posterior; (3) the anterior portion is further divisible into the pars distalis (or anterior lobe proper), the pars tuberalis and the pars intermedia, the posterior portion being designated usually as the neural lobe or pars neuralis; (4) three types of cells are recognizable in the anterior lobe; namely chromophobes, or reserve cells, which lack secretory granules, acidophiles, which contain alpha or acidophilic granules and basophiles, so-called because they contain beta or basophilic secretory granules; (5) the pars anterior is derived from the distal closed end of Rathke's pouch and the pars posterior arises from the infundibulum of the hypothalamic region of the diencephalon; (6) Rathke's pouch develops as a hollow epithelial diverticulum from the roof of the embryonic oral cavity or stomodaeum; (7) the original point of union o