Releasing hormones synthesized in hypothalamic neurons reach their target cells in the anterior pituitary through a specialized vascular route. Which arrangement describes this route?

• A Short portal vessels carry releasing hormones from the posterior pituitary to the anterior pituitary
• B Internal carotid arterial branches supply the anterior pituitary directly, bypassing the hypothalamus
• C Primary capillary plexus in the median eminence drains into long portal vessels supplying the anterior pituitary sinusoids ✓
• D The inferior hypophyseal artery forms the primary plexus that collects hypothalamic releasing hormones

Explanation

Superior hypophyseal arteries form the primary capillary plexus in the median eminence, where axon terminals of hypothalamic neurons discharge releasing and inhibiting hormones. These drain through the long hypophyseal portal veins into the secondary plexus of the anterior pituitary, delivering hypothalamic signals at high local concentration without systemic dilution. The inferior hypophyseal artery mainly supplies the posterior pituitary, so option D misattributes the source.

Reference: Ganong Review of Medical Physiology, 26th ed.

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