Neurosecretory Pathways in the Hypothalamo-Hypophyseal System

Abstract

With mature male mammals as test animals (rats, mice, rabbits and dogs) and by employing the aldehyde-fuchsin method, the substances produced by the hypothalamo-hypophyseal neurosecretory system are investigated and the superior staining affinities of the aldehyde-fuchsin method to the CHP method is confirmed. Pathway of neurosecretory granules are traced and an attempt is made to reveal the fiber connection, especially those between the neurosecretory nerve nuclei of the hypothalamus and the neurohypophysis.1. There are fibers (tractus paraventriculo-hypophyseus) reaching from the nucleus paraventricularis directly to the neurohypophysis. These fibers find their way to the dorsal side of the chiasma opticum or the tractus opticus, pass along in close proximity to each part of the nucleus supraopticus but independently of them and enter the median eminence from all its sides, especially from its rostral and lateral sides.2. There is no pathway of neurosecretory granules in certain fixed areas (A, A1, A2 and A3) around the 3rd ventricle.3. There are fibers reaching from the nucl. paraventricularis directly to each part of the nucl. supraopticus (the pars dorsolateralis, ventromedialis and tangentialis).4. Ther are fibers (tr. supraoptico hypophyseus) reaching from each part of the nucl. supraopticus directly to the neurohypophysis and there is a pathway of secretory granules leading from the pars dorsolateralis either to the pars ventromedialis or to the pars tangentialis.5. Neither the tr. paraventriculo-hypophyseus nor the tr. supraoptico-hypophyseus is detectable in the form of a fiber bundle. The fibers are spread out expansively.6. In rats and mice, there is a pathway of neurosecretory granules leading from the pars dorsolateralis of the nucl. supraopticus to the pars ventromedialis or the pars tangentialis by way of the ventral side of the chiasma opticum and the origin of the tractus opticus.7. A group of neurosecretory cells is detected running through the chiasma opticum in a line or two in the direction of its dorso-ventral side and the granules secreted by them are in connection with those which descend from the nucl. paraventricularis.8. Secretory granules intrude directly into the vascular system at the nucl. paraventricularis, the nucl. supraopticus, the median eminence and the neurohypophysis and into the 3rd ventricle at the nucl. paraventricularis and the median eminence.9. Finding obtained from each of the test animals, -rats, mice, rabbits and dogs, - are almost in perfect agreement.