A major organ of the endocrine system, the anterior pituitary, also called the adenohypophysis, is the glandular, anterior lobe of the pituitary gland. The anterior pituitary regulates several physiological processes including stress, growth, and reproduction.

Its regulatory functions are achieved through the secretion of various peptide hormones that act on target organs including the adrenal gland, liver, bone, thyroid gland, and gonads. The anterior pituitary itself is regulated by the hypothalamus and by negative feedback from these target organs.

The anterior pituitary is composed of multiple parts:

The pars distalis, or "distal part", comprises the majority of the anterior pituitary and is where the bulk of pituitary hormone production occurs. Occasionally, "pars distalis" is incorrectly used as a synonym for the anterior pituitary.
Pars tuberalis

The pars tuberalis or "tubular part", forms a sheath extending up from the pars distalis and wrapping around the pituitary stalk. Its function is poorly understood.
Pars intermedia

The pars intermedia, or "intermediate part", sits between the pars distalis and the posterior pituitary and is often very small in humans

Major Hormones Secreted by Anterior Pituitary Gland

Adrenocorticotropic hormone- Secretion of glucocorticoids

Thyroid-stimulating hormone- Secretion of thyroid hormones

Follicle-stimulating hormone- Growth of reproductive system

Luteinizing hormone- Sex hormone production

Growth hormone- Promotes growth; lipid and carbohydratemetabolism

Prolactin- Secretion of estrogens/progesterone; milk production