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HANDBOOK OF PHYSIOLOGY 



NEUROPHYSIOLOGY II 



FIG. 18. Neurosecretory mate- 

 rial in the central (.4) and distal 

 (B) segments of the supraoptico- 

 hypophyseal tract of the dog after 

 dissection of the tract in vivo. In 

 the central segment (.'1), the fibers 

 appear to be of normal size (/), 

 numerous Herring bodies are 

 present {2) and a large amount 

 of neurosecretory material has ac- 

 cumulated (3). In the distal seg- 

 ment (fi), the fibers are swollen 

 and contain no neurosecretory 

 material i^). A blood clot (j), 

 colloid follicles of the intermedi- 

 ate lobe (6) and transition area 

 of the stalk into posterior lobe 

 (7) can be seen. Chromhema- 

 toxylin-phloxin. [From Hiid & 

 Zetler (172).] 



include the supraoptic and paraventricular nuclei, 

 the fiber tracts of these nuclei into the tuber cinereum 

 and the infundibulum as well as in the posterior 

 lobe (figs. 20, 21; table i). 



The contents of neurosecretory material and poste- 

 rior lobe hormones parallel each other closely during 

 ontogenetic development. Newborn mammals con- 

 tain very little neurosecretory material and a paucity 

 of antidiuretic hormone and exhiljit the so-called 

 physiological diabetes insipidus (29, 42, 79, 83, 156, 

 263). Posterior lobe hormones are demonstrable in the 

 chicken at 9 to 10 days of incubation, whereas the 

 neurosecretory material appears first at 15 to 14 days 



(340), a discrepancy which may be due to greater 

 sensitivity in detecting the former sui:)stance. 



There are marked differences in the amount of 

 both the hormones and the neurosecretory material 

 which are due to different species, various regions of 

 the neurosecretory system and indi\idual variability. 

 Nevertheless, the contents of the hormones and neuro- 

 secretory material always correlate closely (tal:)le 2). 

 In the dog and cat, the hormone and neurosecretory 

 material content of the hypothalamus is particularly 

 rich. Under a wide variety of experimental conditions, 

 the neurosecretor\- material and posterior lobe hor- 

 mones exhibit parallel changes in content (table 3). 



