anterior pituitary

The anterior pituitary is the “factory floor” of the pituitary gland — the part that actually builds and ships out hormones. Unlike its neighbor the posterior lobe, it is true glandular tissue packed with cells that synthesize chemical messengers on demand.

It is regulated not by direct nerves but by chemistry. The hypothalamus secretes releasing and inhibiting hormones into a small portal blood network; these reach the anterior pituitary in concentrated form and tell each cell type how much hormone to make. This indirect, blood-borne control is the defining feature of the anterior lobe.

The anterior pituitary contains several specialized cell types, each producing its own hormone: somatotrophs make growth hormone, lactotrophs make prolactin, thyrotrophs make TSH, corticotrophs make ACTH, and gonadotrophs make LH and FSH. Many of these are tropic hormones — they act on other glands rather than directly on body tissues.

Its output is shaped by feedback. When a target gland's hormone (such as thyroid hormone or cortisol) rises in the blood, it signals back to suppress the relevant anterior pituitary cells, keeping each axis in balance. Failure of these cells causes hypopituitarism; their overactivity, often from a tumor, causes hormone excess.