THE (ESTRUS-PRODUCING HORMONE 113 



(g) SITE OF ORIGIN 



The coincidence of follicular maturation with the occurrence 

 of oestrus, together with the fact that the initial extractions 

 were made from follicular fluid, led to the supposition that 

 the oestrus-producing hormone was essentially elaborated by the 

 mature follicle. More recently, however, the oestrous hormone 

 has been found in situations where it cannot possibly have been 

 elaborated, so that its occurrence in any particular site is not 

 evidence of its origin there. At the time of the first oestrous period 

 no corpora lutea are present in the ovary, and these structures 

 cannot, therefore, be considered as the essential site of origin. 

 In the same way the placenta, also an abundant source of the 

 hormone, is clearly not the essential site of origin. Further, it 

 has been shown that elimination of the Graafian follicles by 

 exposure to X-rays does not prohibit the formation of the 

 oestrus-producing hormone, and it would seem, therefore, that 

 under certain conditions, if not normally, the stromal tissue of 

 the ovary can elaborate the hormone. 



Any hypothesis as to the site of origin of the hormone is 

 necessarily influenced by the view^ taken as to the exact nature of 

 its function (see Chapter VH). 



{h) PHARMACOLOGICAL PROPERTIES 



The pharmacological properties, like the chemical pro- 

 perties, can only be arrived at from negative results ; any 

 positive effect may be caused by impurities. 



Effect on circulation. According to Allen and co-workers (24), 

 Fraenkel (212), Laqueur (346), Doisy, Ralls, and Jordan (166) 

 and Brouha and Simonnet (93), the effect of oestrin on blood 

 pressure is negligible, though crude extracts have a depressor 

 effect. The heart rate is unaltered. Laqueur (346) found no 

 action on the isolated frog heart. 



Respivation. Laqueur (346) found no effect on the respiration 

 of narcotized cats, and later (357) no effect after injection 

 of 2,000 m.u. into the intact dog. 



Metabolism. Laqueur, Hart, and de Jongh (346) found no 

 effect on the blood sugar, but a slight increase in the basal 



P.S.O. H 



