Development of the anterior pituitary gland, from a common primordium in the roof of the embryonic mouth into an organ comprising multiple distinct endocrine cell types, is described by two University of California, San Diego (UCSD) School of Medicine researchers in a review published March 22, 2002 in the journal Science.
M. Geoffrey Rosenfeld, M.D., Howard Hughes Medical Institute investigator and UCSD professor, and Kathleen M. Scully, Ph.D., postdoctoral fellow, UCSD Department of Medicine, provide a step-by-step description of the intricate cell signaling and nuclear events that take place during key steps in pituitary gland development.
Lying at the base of the brain, the pituitary is a pea-sized gland that secretes hormones involved in growth, reproduction, lactation, thyroid gland function, and the maintenance of homeostasis (i.e. a constant internal environment). The gland is a complex organ regulating a combination of neural signals from the hypothalamus as well as feedback from target organs.
In recent years, researchers have begun to identify some of the molecules that direct the series of developmental steps by which precursor cells gain a pituitary identity, proliferate, and differentiate to form the distinct hormone-producing cell types of the mature gland, Scully says.
In their Science review article, the researchers describe an initial external signaling phase where cells surrounding the pituitary primordium secrete molecules that start the developmental process. Eventually, the developing gland itself begins secreting some of these molecules, which help to establish its identity and facilitate growth. During this time, expression of certain transcription factors, that function as molecular switches turning genes on and off, must be activated or repressed in order for the pituitary gland to progress to the next step in its development.