Co-existence of gonadotrophins (FSH, LH) and thyrotrophin (TSH) in single anterior pituitary cells of the musk shrew, Suncus murinus

According to recent immunocytochemical studies of anterior pituitary cells, it is obvious that the "one cell-one hormone" theory must be modified. Many pituitary morphologists have demonstrated that there are some cells that contain two hormones. In this study, we demonstrate by means of immuno-electronmicroscopy the co-existence of gonadotrophins (FSH and LH) and thyrotrophin (TSH) in the same anterior pituitary cells of the musk shrew. These cells were remarkably altered in their ultrastructural features by either gonadectomy or thyroidectomy. Double labeling for gonadotrophins and thyrotrophin was present not only in the same cells but also in the same secretory granules. Our ability to demonstrate co-existence of gonadotrophins and thyrotrophin in the same cell may be due to our selection of fixative and embedding media for electron-microscopic immunocytochemistry. Our conclusion that gonadotrophins and thyrotrophin are produced in a single cell type of the anterior pituitary gland in the musk shrew, i.e., thyrogonadotrophs, suggests the need to consider a modification of the classic scheme for classification of anterior pituitary cells.