Identification of Human Anterior Pituitary Cells by Immunoelectron Microscopy

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Abstract
An attempt was made to classify human pituitary cell types by electron microscopic immuno-histochemistry. The immunoperoxidase technique involving the use of the peroxidase-antiperoxidase complex was applied to thin sections of human pituitaries removed surgically for breast cancer or diabetic retinopathy. Using specific antibodies against human PRL, GH, β-FSH, β-LH, β-TSH, and porcine ACTH, the localization of each hormone was studied. Identification of 5 human pituitary cells was possible: 1) The PRL-secreting cell contains round or slightly ovoid secretory granules of a diameter of 275–350 nm. 2) The GH-secreting cell is densely granulated with granule diameters ranging from 350–500 nm. 3) The gonadotrophic cell, which stains for both β-FSH and β-LH, is characterized by the presence of a varying number of secretory granules ranging from 275–375 nm. 4) The cortico-lipotrophic cell has numerous granules of about 375–550 nm in diameter. 5) The TSH-secreting cell contains small secretory granules of about 125–200 nm in diameter. Another cell type of which the small secretory granules of about 100 nm n i diameter could not be stained by any of the antisera was also observed. This ultrastructural identification of human pituitary cells should contribute to a better understanding of the pathophysiology of the human pituitary.