THE PITUITARY BODY 



the hypothalamus; however, it is doubtful if it is not then 

 secondary to an additional change in the pars glandularis. 



The presence in the hypothalamus and in the cerebrospinal 

 fluid of substances resembling the active principles of the pars 

 neuralis. — As will be pointed out later in chapters dealing 

 with the effects of extracts of the pars neuralis, cerebrospinal 

 fluid has been found to stimulate the isolated uterus and to 

 raise the blood pressure. To the observers, these results have 

 often seemed to prove that the pars neuralis secretes its active 

 principles into the cerebrospinal fluid as postulated by Her- 

 ring, Gushing, and others, hx present, however, the physio- 

 logical evidence is far too equivocal to permit the acceptance 

 of this belief. For example, the isolated uterus of the guinea 

 pig, which is used extensively for the assay of extracts of the 

 pars neuralis, can probably be stimulated by many organic 

 substances other than histamine and the oxytocic principle of 

 the posterior lobe; apparently the calcium-ion of cerebro- 

 spinal fluid also will cause a contraction of the isolated uterus 

 and thus mimic the true oxytocic principle (van Dyke, 

 Bailey, and Bucy, 1929). A pressor principle can be extracted 

 from cerebrospinal fluid, ascitic fluid, and blood (Page, 1935). 

 Its pressor effects, however, disappear after the destruction 

 of the central nervous system; so it cannot be identical with 

 the pressor principle of the pars neuralis. 



Geesink and Koster (1928) concluded that the concentra- 

 tion of the oxytocic principle in the cerebrospinal fluid was 

 reduced in hypophysectomized dogs. In the same year, Tren- 

 delenburg and Sato reported that an apparently normal 

 amount of oxytocic principle could be found in the cerebro- 

 spinal fluid some time after hypophysectomy; they believed 

 that this was vicariously produced in the tuber cinereum 

 from which they were able to make extracts having oxytocic 

 and antidiuretic-chloride-concentrating properties. Such ex- 

 tracts were found to be more powerful if made from the tu- 

 ber cinereum of hypophysectomized dogs. Sato (1928) also 



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