10^8 HANDBOOK OF PHYSIOLOGY ^ NEUROPHYSIOLOGY II 



PARS INTERCEREBRALIS Of BRAIN 



ACCUMULATION OF NEUROSECRETORY 

 MATERIAL PROXIMAL TO SITE Of 

 NERVE SECTION 



NERVUS CORP CARDlACI WITH 

 UNOBSTRUCTED l»LOW OF 

 NEUROSECRETORY MATERIAL 



STORAGE OF NEUROSECRETORY 

 MATERIAL IN CORP CARDlACUM 

 OF NORMAL Side 



DEPLETION OF NEUROSECRETORY 

 MATERIAL IN CORP CARDlACUM 

 OF OPERATED SIDE 



NORMAL CORP ALLATUM 



LARGER CORP ALLATUM OF 

 OPERATED SIDE 



FIG. 28. Diagram of the dorsal aspect of the intercerebraHs-cardiacum-allatum system of Leuco- 

 phaea maderae. On the left side the nervus corporis cardiaci is severed with the result that neurosecretory 

 material is increased proximal to and is depleted distal to the site of nerve section. On the operated 

 side the corpus cardiacum is decreased, the corpus allatum increased in size. [From Scharrer (278).] 



tions on the basis of its refractive properties. 

 Neurosecretory cells frequently exhibit considerable 

 vacuolation in certain functional stages of activity 

 (fig. 26). Neurosecretory pathways are particularly 

 apparent in many forms (fig. 27), with their direction 

 of transport being readily demonstrated by transection 

 and even ligation of the tract, as shown in figure 28 

 (278, 322, 337). Bead-like accumulations of neuro- 

 secretory material have been observed along the 

 axons of living nerve fibers. As in the case of verte- 

 brates, the neurosecretory elements in invertebrates 

 possess conductional capacity [Mil burn, quoted by 

 Bliss (49)] the physiological significance of which is 



unknown. B\- and large, the morphological as well as 

 physiological and biochemical (260) aspects of neuro- 

 secretion have been investigated more intensively in 

 the invertebrate kingdom. However, no single case 

 has received the attention paid to the supraoptico- 

 hypophysis system. Two basic principles of hypo- 

 thalamic-pituitary relationship have been well 

 established for invertebrates; a) the neurosecretory 

 material is carried over neuronal pathways to a depot 

 or reservoir from which it is released into the blood 

 stream or the peripheral tissues according to the 

 needs of the organism and b) the neurosecretory ma- 

 terial delivered to the glands of internal secretion 



