Human pharyngeal and sellar pituitary glands: differences and similarities revealed by an immunocytochemical study

Abstract

ABSTRACT Fifteen pharyngeal and sellar pituitary glands, obtained at autopsy from unselected adult patients, were compared in an attempt to elucidate the functional significance of the pharyngeal pituitary. The study was carried out using light microscopy and an indirect peroxidase technique to detect the presence of prolactin, GH, ACTH, LH, FSH, TSH and lipotrophin (LPH) immunoreactive cells. A quantitative analysis of these cell types in each gland was performed. Neither the pharyngeal nor the sellar pituitaries were abnormal in six cases. In this group the average percentage of immunoreactive cells in the sellar vs the pharyngeal pituitary was 11·3 vs 7·4 for FSH cells, 13·3 vs 4·4 for LH cells, 6·4 vs 5·2 for TSH cells, 14 vs 1·5 for ACTH cells, 13·1 vs 6 for LPH cells, 29·4 vs 5·2 for GH cells and 21·2 vs 8·5 for prolactin cells. A comparative statistical evaluation of the seven hormone-producing cell types indicated that, in most cases, the percentage of immunoreactive cells was significantly higher in the sellar pituitary. Examination of serial sections revealed hyperplasia, with or without microadenomas, in nine sellar pituitaries. In these abnormal cases most of the pharyngeal pituitary glands showed hyperplasia of the same cell type as was found hyperplastic in the sellar adenohypophysis. However, hyperplasia restricted to the sellar pituitary was also seen. There were two cases in which the pharyngeal pituitary was almost lacking in immunoreactive cells; in one of them the sellar pituitary had GH and prolactin cell hyperplasia. The results obtained confirm that under normal conditions the pharyngeal pituitary is not an important source of adenohypophyseal hormones. They also suggest that the pharyngeal pituitary, despite its capacity to respond at a cellular level, has a limited potential in terms of volume, and that it is not developmentally programmed to replace the sellar adenohypophysis except when the latter has a serious pathological condition. J. Endocr. (1986) 108, 231–238