The pituitary stalk (also known as the infundibular stalk, Fendersons funnel, or simply the infundibulum) is the connection between the hypothalamus and the posterior pituitary. The floor of the third ventricle is prolonged downward as a funnel-shaped recess—the infundibular recess—into the infundibulum, where the apex of the pituitary is attached. It passes through the dura mater of the diaphragma sellae as it carries axons from the magnocellular neurosecretory cells of the hypothalamus down to the posterior pituitary where they release their neurohypophysial hormones, oxytocin and vasopressin, into the blood. This connection is called the hypothalamo-hypophyseal tract or hypothalamo-neurohypophyseal tract. Damage to the pituitary stalk blocks the release of antidiuretic hormone, resulting in polydipsia (excessive water intake) and polyuria (excessive urination). The diameter of the pituitary stalk at the level of optic chiasm is 3.3 mm, and at the pituitary gland insertion site is measured at 1.9 mm. See also
Pituitary stalk interruption syndrome

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Hypopyon is a medical condition involving inflammatory cells in the anterior chamber of the eye. It is an exudate rich in white blood cells, seen in the anterior chamber, usually accompanied by redness of the conjunctiva and the underlying episclera. It is a sign of inflammation of the anterior uvea and iris, i.e. iritis, which is a form of anterior uveitis. The exudate settles at the dependent aspect of the eye due to gravity. It can be sterile (in bacterial corneal ulcer) or not sterile (fungal corneal ulcer). Differential diagnosis
Hypopyon can be present in a corneal ulcer. It can occur as a result of Behçets disease, endophthalmitis, panuveitis/panophthalmitis, or adverse reactions to some drugs (such as rifabutin).Hypopyon is also known as sterile pus because it occurs due to the release of toxins and not by the actual invasion of pathogens. The toxins secreted by the pathogens mediate the outpouring of leukocytes that settle in the anterior chamber of the eye. An inverse hypopyon is different from a standard hypopyon. Inverse hypopyon is seen after a pars plana vitrectomy with an insertion of silicone oil (as a replacement of the vitreous humour that has been removed in the operation; the silicone oil maintains internal tamponade). When the silicone oil emulsifies, it seeps into the anterior chamber and settles at the top of the anterior chamber. This is in contrast to hypopyon resulting from toxins where the leukocytes settle at the bottom of the anterior chamber.