True statements about pituitary anatomy and physiology include:

A. The pituitary has dual embryonic origin: the anterior pituitary arises from embryonic ectoderm; the posterior pituitary, from the diencephalon.

C. Adrenocorticotropin (ACTH), formed by posttranslational processing of the precursor POMC, is normally controlled by hypothalamic CRF but may be released by immune-related mechanisms.

DISCUSSION: The anterior pituitary arises from Rathke's pouch (embryonic ectoderm), and it includes the pars distalis, pars intermedia, and pars tuberalis. The posterior pituitary arises from the diencephalon and includes the neural stalk, infundibulum, and posterior lobe. The hypophyseal portal system drains from the hypothalamus and integrates function of the hypothalamus and anterior pituitary by carrying hypothalamus-derived releasing factors to target cells in the anterior pituitary. ACTH may be released during stress in response to interleukin-1, -2, and -6. Somatotrophic actions of GH are indirect and are mediated by the insulinlike growth factors formerly known as somatomedins. Current classification of anterior pituitary cells is based on immunochemical identification of their secretory products (i.e., corticotropes produce ACTH, lactotropes produce prolactin, and thyrotropes produce thyroid-stimulating hormone [TSH]).