Glial fibrillary acidic protein-positive cells in human anterior pituitary--immunohistochemical and ultrastructural study.

The GFAP-positive cells in the five human anterior pituitaries obtained at autopsy were investigated immunohistochemically and ultramicroscopically. The GFAP-positive cells varied in number from case to case and were identical with the so-called stellate cell. The stellate cells were also involved in the follicular formation. The electron microscopic study showed the various features of these cells. Some had a narrow rim of perikaryon and slender cytoplasmic processes with a moderate number of mitochondria and endoplasmic reticula and others formed an intercellular lumen and follicles with well developed Golgi apparatus, vesicular body and lysosome. The intermediate filaments were rather abundant and the anit-GFAP-positive products were thought to be related with these filaments. The stellate cells were non-granulated so far as examined. The variability of their ultrastructural features were thought to reflect the different physiological state of the pituitary. The present findings suggested the important role of the stellate cells in the function of the endocrine secretary cells. Their origin was also discussed.