Figure 12. Magnified view of a fixed human brain in midsagittal orientation. The third ventricle makes up the core of the hypothalamus and extends into the pituitary (or infundibular) stalk, creating the infundibular recess. Many of the major cell groups are located near the midline. These include (from rostral to caudal) the preoptic nucleus (Pop), paraventricular nucleus (Pvn), dorsomedial nucleus (Dm), ventromedial nucleus (Vm), arcuate (or infundibular) nucleus (If), posterior hypothalamic nucleus (Po), and medial mammillary nucleus (mm). Ac = anterior commissure, fx = fornix, lt= lamina terminalis, ot = optic tract and chiasm, Lv = lateral ventricle, MB = midbrain, PN = pons, Sr = supraoptic recess, T = thalamus. (From Lechan R.M. and Toni R., Regulation of Pituitary Function, in Korenman S.G (Ed), Atlas of Clinical Endocrinology, Current Medicine, vol IV, 1-25, 2000).