Answer is pituitary gland.
In order to stimulate or inhibit the hormones produced by the endocrine glands, signals are sent to these endocrine glands by the hormones secreted by the pituitary gland.
Consider the following example. When a person is stressed in order to stimulate the production of cortisol, the anterior pituitary lobe will release adrenocorticotropic hormone (ACTH).
