PARS NEURALIS AND INTERNAL SECRETION 



Engle (1936), 400-500 rat-units of oestrin were injected daily 

 for 10 days into young or adult hypophysectomized monkeys. 

 After injections were stopped, delayed bleeding was observed 

 in 8 instances. In 2 instances bleeding did not occur. The 

 authors were loath to attribute the delay in or absence of 

 bleeding to a specific factor. 



SUMMARY 



Contrary to the view previously expressed (van Dyke, 

 1936), there is now good evidence that the pars neuralis is an 

 important gland of internal secretion. The best data have 

 been gathered in studies of the metabolism of water. In the 

 normal mammal, it seems probable that the reclamation of 

 water filtered through the glomeruli of the kidney when urine 

 is secreted depends upon the diuresis-inhibiting (vasopressor) 

 hormone of the pars neuralis. If a dangerous loss of water 

 from the body is threatened, diuresis-inhibiting hormone is 

 secreted at an increased rate and by its local action on the 

 tubular epithelium of the kidneys increases the rate of re- 

 absorption, and hence the conservation, of water. The nerv- 

 ous control of the secretion of diuresis-inhibiting hormone 

 appears to be of the greatest importance and explains how 

 afferent stimuli can affect (inhibit) the secretion of urine 

 after renal denervation. In an animal like the cat the paired 

 supraoptic nuclei of the hypothalamus apparently supply 

 most of the secretory fibers of the pars neuralis which under- 

 goes atrophy and secretes little or no hormone if the nuclei 

 have been destroyed or the fibers have been cut, as after sec- 

 tion of the stalk. Under such circumstances, the kidneys lose 

 their ability to concentrate urine, so that water loss, poly- 

 uria, is abnormally rapid. In compensation the animal drinks 

 an increased volume of water (polydipsia). The changes, 

 therefore, are analogous to diabetes insipidus in man. 



Furthermore, it appears that the function of another part 

 of the pituitary, the pars glandularis, is necessary for the 



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