The pituitary is a small endocrine organ in the sphenoid bone under the hypothalamus. Primarily, the pituitary in adults has two distinct anatomical and functional regions— the anterior and posterior lobes. During human fetal development, a third pituitary gland region called the pars intermedia atrophies and disappears. However, some of its cells migrate and exist adjacent to the anterior pituitary in adults.
The posterior pituitary lobe has two parts: the infundibulum, a funnel-shaped stalk, and the pars nervosa. The infundibulum allows the passage of the supra-optic and paraventricular nuclei axons of the hypothalamic-hypophyseal tract, maintaining a neural connection with the hypothalamus. The hypothalamic-hypophyseal tract delivers hormones secreted by hypothalamic neurosecretory cells into the posterior pituitary lobe for storage and release.
