EM 316 Pituitary

Hypophyseal Portal System

Perfusion of tissue with a polymer resin and subsequent removal of the tissue produces a vascular cast. Scanning electron microscopy of the cast provides detailed information about the blood supply to a tissue.

Scanning electron micrograph (SEM) of a vascular cast of the hypothalamic-hypophyseal portal system.

• Arteries divide into a plexus (tan) that supplies the median eminence of the hypothalamus.
• These capillaries rejoin to form larger venules (yellow) that travel a short distance to the anterior pituitary (adenohypophysis).
• There it branches again to form a larger secondary capillary plexus (green).

This arrangement quickly transports releasing and inhibiting hormones from the hypothalamus to the anterior pituitary.

Larger Blood Vessels

• Arteries (red)
• Veins (blue)

Courtesy of Osamu Ohtani, Department of Anatomy, Tokyo Medical University, Tokyo, Japan.