DEVELOPMENT AND DIFFERENTIATION OF PITUITARY-CELLS

Classically, it was thought that the adenohypophyseal gland originated from the oral ectoderm. Its development has been the object of numero us studies over many years. However, several questions are still raise d about its origin, differentiation, and commitment. The adenohypophys eal gland could originate from the anterior ridge of the neural plate. Glandular adenohypophyseal cells are committed very early in embryoni c life. Interactions between adenohypophyseal presumptive territory an d neighboring tissues can exist very soon, as early as at the open neu ral stage. The expression of a given phenotype by the committed cells seems to be controlled by a number of differentiation and/or transcrip tion factors. In view of all these studies, performed with the use of different in vivo and in vitro models, classical concepts of the embry ology of the adenohypophyseal gland need to be reevaluated. Indeed, ma ny questions remain unanswered concerning the molecular mechanisms of known and unknown factors controlling development of the adenohypophys eal gland. (C) 1997 Wiley-Liss, Inc.