anterior pituitary

The anterior pituitary (or adenohypophysis) is by far the largest part of the pituitary gland, and is responsible for synthesis and release of most pituitary hormones (with the exception of oxytocin and antidiuretic hormone (ADH) which are released by the posterior pituitary).

It consists of 3 parts:

Pars distalis

The pars distalis is the largest part of the pituitary gland. It forms from the anterior wall of Rathke pouch. It is composed of cords of epithelial cells individually specialized to secrete tropic hormones acting on target organs:

  • growth hormone (somatotropin)
  • thyroid stimulating hormone (TSH)
  • adrenocorticotropic hormone (ACTH)
  • follicular stimulating hormone (FSH)
  • leutinizing hormone (LH)
  • prolactin
  • Pars tuberalis

    The pars tuberalis is the part of the adenohypophysis which surrounds the anterior aspect of the infundibular stalk.

    Pars intermedia

    The pars intermedia in a thin layer of epithelial cells located between pars distalis and neurohypophysis. It arises from the posterior wall of Rathke pouch and contains vestigial lumina of Rathke pouch which appear as narrow vesicles of variable length. These may give rise to Rathke cleft cysts (also known as pars intermedia cysts ).

    For relations and blood supply, please see the main pituitary gland article here.