Physiology Posterior pituitary hormone secretion is mediated by: A A portal capillary system from the hypothalamus to the posterior pituitary B The fight-or-flight response C The hypothalamo-hypophyseal tract originating from magnocellular neurons in the supraoptic and paraventricular nuclei D The reticular activating system's input to the hypothalamus 💡 Explanation Posterior pituitary hormone secretion is mediated by: ✓ Correct Answer: C. The hypothalamo-hypophyseal tract originating from magnocellular neurons in the supraoptic and paraventricular nuclei