Immunohistochemical localization of certain inducers related to the proliferation of the pituitary gland and a study on cell contacts between the presumptive neurohypophysis and the adenohypophysis in the foetal mouse.

Optic and confocal laser scanning microscopy (CLSM) and the LsAB method were used to immunolocalize TGF alpha, EGF, FGF-2 and their related receptors, which are involved in the regulation of organogenesis in the mouse hypophysis. Internalization of the above receptors and the active proliferation of the presumptive adenohypophysis and neurohypophysis were observed during the mid-foetal stage. CLSM images were used to map the distribution of Cx32 in the proliferating hypophysis, particularly between the closely apposed neuro- and adenohypophyses. Using conventional transmission electron microscopy, gap junctions were observed at the boundary of these structures. The results suggest that cell coupling via gap junctions may provide positional information that is then used to control the differentiation of the hypophyseal cells.