226 



HYPOPHYSIS AND GOXADOTROPHIC HORMONES 



duction of this clirome-alum hematoxylin 

 staining method revolutionized both the 

 technical side of investigations of neuro- 

 secretion and the interpretation of its sig- 

 nificance. With this method it became clear 

 that the grosser collections of neurosecretion 

 detected by earlier methods, which occur 

 only in an erratic fashion, constituted but 

 a small part of the hypothalamic neuro- 

 secretion which is found in neurones of 

 every vertebrate hypothalamus (Bargmann 

 and Hild 1949; Hild, 1950; 1951a, b; Barg- 

 mann, Hild, Ortman and Schiebler, 1950). 

 The neurosecretory material could be seen 

 throughout the course of the supraoptico- 

 and paraventriculo-hypophyseal tracts and 

 their continuations in the neural eminence 

 and stalk into the pars nervosa (Fig. 3.33). 

 The greater part of the stainable neuro- 



FlG.3.33(w/^/n, ). (■(.rnii;,! ,M.-n.,n ..I il.c I,n|m,|,|,- 

 ysis of a normal rat stained with dilute uldehydc- 

 fuchsin (AF) after permanganate oxidation. The 

 pans nervosa contains a large amount of darkly 

 stained neurosecretion. P.N. pars nervosa; P.I., 

 pars intermedia; PA., pars anterior. KMnOi , AF, 

 X50. 



Fig. 3.34 (loirer). Coronal section of tlie liypojili- 

 ysis of a rat which was deprived of drinking water 

 for 5 daj^s. An extreme reduction in the content of 

 neurosecretion is apparent in comparison with Fig- 

 ure 3.33. Key to lettering as in Figure 3.33. KMnO, , 

 AF, X 50. 



secretion in mammals is found in the nerve 

 fiber terminals in the pars nervosa; the 

 amount in other parts of the hypothalamo- 

 neurohypophyseal system in some species 

 and especially in j^oung animals may be in- 

 significant by comparison. The distribution 

 corresponds to that of the neurohypophyseal 

 hormones. 



In addition to demonstrating the exact 

 distribution of neurosecretion, specific stain- 

 ing made it possible to demonstrate that 

 the material formed in the perikaryon is 

 transported, probably by axoplasmic flow, 

 towards the pars nervosa. After stalk sec- 

 tion the stainable neurosecretion accumu- 

 lates in the proximal stump of the transected 

 axons <Hild, 1951b; Hild and Zetler, 1953; 

 Scharrer and Scharrer, 1954). 



Depletion of stainable neurosecretion in 

 the pars nervosa occurs in animals subjected 

 to dehydration (Hild and Zetler, 1953; 

 Leveque and Scharrer, 1953). The loss of 

 stainable material is almost complete in 

 animals subjected to prolonged water dep- 

 rivation (Fig. 3.34) and parallels the loss 

 of hormone content. It is clear that dehydra- 

 tion is a powerful stimulus to the release of 

 stainable neurosecretion from the pars ner- 

 vosa and that the material released is 

 either itself hormonally active or is ac- 

 companied by the hormones. Moreover, pro- 

 longed dehydration causes a depletion of 

 both stainable neurosecretion and of hor- 

 mone activity in the neurones and axons of 

 the supraoptic and paraventricular nuclei in 

 the hypothalamus. This shows that the hor- 

 mone activity accompanies the stainable 

 neurosecretion in its passage along the 

 axons, the transport of both being acceler- 

 ated by the stimulus of dehydration. 



From these observations it is inferred that 

 tlie neurohypophyseal hormones are pro- 

 duced in the perikarya of the neurones of 

 the supraoptic and paraventricular nuclei 

 and are transported along the axons to the 

 fiber terminals from which they are_ re- 

 leased to be carried away by the adjacent 

 blood vessels. In their formation, transport, 

 and release the hormones are accompanied 

 by or form part of a specific protein, the 

 stainable neurosecretory substance. Obser- 

 vations of the type presented above have 

 been repeated in a number of different spe- 



