Mixed growth hormone- and prolactin cell adenomas of the pituitary gland. An immunoelectron microscopic study.

The morphological features of seven pituitary adenomas producing both growth hormone (GH) and prolactin (PRL) are reported. Up to five different cell types within the same tumour were observed by applying single and double immunoelectron microscopical staining methods. Despite the occurrence of some mammosomatotropic cells in three of the seven cases all fit into the group of mixed GH- and PRL cell adenomas. The mammosomatotropic cells in two cases were found to express GH and PRL in the same and different granules whereas in the third case the hormones were packed only in different granules.