In order to investigate the anatomical and functional relationships between pituitary adenomas, residual pituitary glands and pituitary capsule, 24 surgical specimens and 26 autopsy materials (8 acromegalies, I 1 PRL producing adenomas, 9 non-functioning adenomas, 22 subclinical microadenomas) were studied by the peroxidase-labeled antibody method for the localization of various pituitary hormones.
Usually well-delineated interface was found between adenoma and gland, while superficial invasions of tumor cells were observed locally in a few cases. On the other hand, when smaller than 2 mm in diameter, the adenoma had somewhat irregular boundaries, containing a few anterior pituitary cells in its parenchyma.
Even in the advanced cases with suprasellar extension, several compressed normal layers with intact immunoreactivity were often found between tumor and diaphragma sellae. A small amount of invasion was seen in some pituitary capsule to which the adenoma was directly related.
Neither hyperplasia nor pathological cell populations were detected in the residual gland of all of the adenoma examined. Irrespective of tumor functions, cell proportions of the residual glands were as follows: GH≈PRL>ACTH>TSH, FSH.
From the above findings, the assessment of operative procedures and the patterns of tumor growth are also discussed.