The Cytogenesis and Pathogenesis of Pituitary Adenomas*

I. Introduction: Pituitary Adenomas A. Definition B. Epidemiology C. Classification II. Pituitary Cytodifferentiation A. Early pituitary development B. Pit-1 C. CREB D. Estrogen receptor (ER) E. Thyrotroph embryonic factor (TEF) F. Steroidogenic factor-1 (SF-1) G. Corticotroph upstream transcription-binding element (CUTE) H. Other putative factors I. A model of adenohypophysial cytodifferentiation III. Pathogenetic Mechanisms in Pituitary Adenoma Development and Progression A. Hormonal factors B. Molecular events C. Growth factors and receptors D. An integrated approach to multistep tumorigenesis IV. Concluding Comments