MH 149 Pituitary

Pituitary

The pituitary gland is composed of an anterior and posterior lobes.

• Anterior Pituitary - contains three divisions;
  • Pars Distalis - comprises most of the anterior lobe (~75%) and contains five types of endocrine cells.
    • Chromophils - stain with H&E and secrete hormones.
      • Acidophils - stain pinkish-red with H&E.
        • Somatotrophs - growth hormone (GH).
        • Mammotrophs (Lactotrophs) - prolactin.
      • Basophils - stain bluish-purple with H&E.
        • Corticotrophs - ACTH.
        • Thyrotrophs - TSH.
        • Gonadotrophs - FSH and LH.
    • Chromophobes - stain poorly with H&E and do not secrete hormones.
    • Fenestrated Capillaries - extensive network that receives hormones from acidophils and basophils.
  • Pars Tuberalis - not shown.
  • Pars Intermedia - thin remnant (<2%) at interface between the anterior and posterior lobes that contains numerous colloid (protein)-filled cysts (Rathke's cysts; #1,#2).
• Posterior Pituitary - axons from the hypothalamus that release hormones into the capillaries of the pars nervosa.
  • Pituicytes - most nuclei belong to glial cells.
  • Herring Bodies (#1,#2,#3,#4,#5) - dilations of axons filled with neuro-secretion vesicles.