Abstract
The prolactin (PRL) production and ultrastructure of two human pituitary adenomas subjected to routine fixation and embedding for transmission electron microscopy were studied by a consecutive semithin-thin section method.The method allowed highly specific immunostaining for PRL on Epon embedded semithin sections and excellent preservation of ultrastructure on the adjacent thin sections.
Immunostaining for PRL by the unlabeled peroxidase-antiperoxidase method on semithin sections after removal of the Epon well delineated the region of immunoreactivity, which corresponded both to the Golgi areas and to the distribution of secretory granules. The cytoplasm of most cells was not diffusely immunostained. Electron microscopy of the adjacent section revealed that the Golgi membranes were highly developed, that scant number of small secretory granules measuring about 160 nm in diameter were scattered in the Golgi areas and along the plasma membrane, and that the so-called misplaced exocytosis (pinching-off of secretory granules to the intercellular space of adenoma cells) existed in most PRL-positive cells. This method confirmed the direct ultrastructural characterization of PRL producing adenoma cells and their difference from non-neoplastic human pituitary PRL cells.
