Endocrine cell. Coloured transmission electron micrograph (TEM) of a cultured endocrine cell. Endocrine cells are part of the endocrine system. They release chemical messengers (hormones) from secretory granules (black). The hormones are transported via the bloodstream to target cells in other tissues. Hormone actions include stimulation or inhibition of growth, induction or suppression of cell death (apoptosis), activation or inhibition of the immune system and regulation of metabolism.