CELL CONTACTS IN EARLY HUMAN PITUITARY DEVELOPMENT

The ultrastructure cell and tissue contacts in the developing human pi tuitary gland were studied in embryos from 3 to 5 weeks of age. At the early stage, the pituitary anlage, Rathke's pouch (RP) of the pharyng eal gut wall, had no direct contact with the diencephalon. At later st ages, several close cell-to-cell contact sites were observed between t he two tissues, on the upper anterior aspect of RP. However, even at t hese contact sites a thin layer of extracellular material always remai ned between the tissues, elsewhere covered by a well-developed basemen t membrane. cells during the to different tissue interaction models.