[Morphology and electron microscopic structures of pituitary gland]

This article describes and illustrates a brief summary of the electron microscopic features of the cell types in the anterior pituitary gland on recent works done on animals or man. Fundamentally, the shape and size of secretory granules in the anterior pituitary cells are still available for functional cell classification today, but the morphology of secretory granules is not homogeneous even in single cells and various depend on different kinds of animals or man. In addition, co-localization of two or more hormones or peptide (s) has been observed in some single cells. Consequently, the "one cell-one hormone" concept has been fully withdrawn and more reasonable cell classification of anterior pituitary cells will be revised in the near future.