Anatomy of the tuberoinfundibular system in the rat, demonstrated by retrograde transport of a tracer compound.
A tracer compound, wheat germ agglutinin (which is taken up by nerve endings), was injected into the median eminence of a rat. Several hours later, the animal was killed and the brain sectioned and stained immunohistochemically with an antibody to wheat germ agglutinin. The tracer was found in cell bodies located in three main areas: (a) the arcuate nucleus; (b) the periventricular nucleus, which comprises a rich plexus that is several cells deep immediately under the ependymal layer of the third ventricle; and (c) the paraventricular nuclei. Many of the arcuate cells are dopaminergic, and most penventricular cells are somatostatinergic. The paraventricular nucleus is complex and includes cells that secrete ADH oxytocin, TRH, somatostatin, neurotensin, CRH, VIP, and many other hormones. In addition to projecting to the median eminence (for control of anterior pituitary secretion), the paraventricular nucleus projects to other regions of the neuroaxis where other visceral regulating functions are carried out. By courtesy of Dr R Lechan.
