Origin of adenohypophysial lobes and cells from Rathke's pouch in Swiss albino mice. Proliferation and expression of Pitx 2 and Calbindin D28K in corticotropic and somatotropic cell differentiation.

A developmental study of the adenohypophysis of the mouse was carried out in response to several as yet unanswered questions about its organogenesis and differentiation. The main objectives were to establish the origin of adenohypophysial lobes and cells from the Rathke's pouch (RP) and elucidate the mechanisms of development and functional differentiation of the gland. Using diverse techniques, the morphological development, proliferation and differentiation were studied in order to delimit different proliferative regions in the RP, and provide a satisfactory explanation for the distribution of each cell type in the adult gland. Combining the proliferation and differentiation studies, corticotropic and somatotropic cells appear to mainly originate from undifferentiated precursors located within each of these proliferative regions. The involvement of transcription factor Pitx 2 and calcium-binding protein Calbindin D 28K in the differentiation of corticotropic and somatotropic cells is further clarified.