NEUROSECRETION 



1049 



FIG. 16. Supraoptic nucleus of 

 the rat; A, normal; B, after 15 

 days of water deprivation, show- 

 ing increase in size of the nuclei 

 and nucleoli and peripheral dis- 

 position of the Nissl substance; C, 

 degenerating neuron seen after 

 two injections (3.6 per cent of 

 the body weight) of 5 per cent 

 sodium chloride. Chromhema- 

 toxylin-phloxin. X 470. 



secretory material in all segments of this system, a 

 findins; interpreted as an adaptation with subsequent 

 liyperfunction. 



Transection of the supraopticohypophyseal tract 

 has been carried out with many variations (46, 172, 

 179, 191, 215, 224, 290, 316, 317) and leads to an 

 accumulation of neurosecretory material proximal 

 to the cut (fig. iQA), while distal to the section (fig. 

 i8fi) only a depletion of the neurosecretory material 

 is observed (86, 165, 172, 215, 316, 317). After transec- 

 tion of the stalk, the neurosecretory material in the 

 posterior lobe is removed only slowly, even under 

 those conditions which normally evoke a rapid 

 depletion (165). Correspondingly, if the posterior lobe 

 is first depleted of neurosecretory material, it will 

 remain so after transection of the tract. In the usual 

 transection experiments, the region proximal to the 

 cut accumulates a content of neurosecretory mate- 

 rial which is far greater than ever observed under nor- 

 mal conditions. A similar situation of accumulation 

 of neurosecretory material has been observed in 

 man when obstructive tumors block the neurosecre- 

 tory pathways (227). Three to four weeks after hypo- 

 physectomy of the rat, the infundibular stump under- 

 goes changes which resemble a regeneration (fig. 19), 

 including a rich vascularization of the reorganized 

 glial material and subsequent accumulation of neu- 

 rosecretory material (122, 124, 179, 290, 316, 317). 

 This depot of neurosecretory material can be exper- 

 imentally depleted but only under intensive stim- 

 ulation such as simultaneous salt load and admin- 

 istration of desoxycorticosterone (46). These findings 

 may explain some of the consequences of hypophysec- 

 tomy observed experimentally as well as clinically. 

 The remission of diabetes insipidus following hy- 

 pophysectomy, for example, may be correlated with 



Nudeolusdurchmesser im Ncl pararentricularis 



n 



' I i I 



JS07. 



WO'/. 



^85 



10 



15 ToK/s 



FIG. 17. Graph of nucleolar size in neurons of the para- 

 ventricular nucleus of the rat following water deprivation. 

 [From Ortmann (237).] 



the renewed secretion of antidiuretic hormone from 

 the infundibular stump (177). In the toad, a true 

 regeneration of fibers of the preoptic-hypophyseal 

 tract has been described (180). 



The experiments of Hild & Zetler (168-172, 343, 

 344) indicate that the content of neurosecretory mate- 

 rial is closely correlated with the hormone content 

 in the posterior lobe (figs. 20, 21). These were con- 

 firmed by other workers (6, 26, 67, 82, 225, 285, 333). 

 In all species studied, tho.se areas of the nervous 

 system which contain posterior lobe hormones always 

 contain neurosecretory material al.so. The.se areas 



