CHAPTER VII 



THE FUNCTION OF (ESTRIN 



{a) ACTION OX TEST ANIMALS 



Ik test animals, the effect of injection of oestrin in adequate 

 amounts is to produce all the extra-ovarian histological and 

 ph3^siological symptoms of the normal oestrous period, except 

 possibly the mating instinct. The uterus of the ovariectomized 

 rabbit undergoes hypertrophy after injection, until a condition 

 similar to that of the normal oestrous uterus is attained. In the 

 immature uterus this involves a very considerable increase in 

 size. Injection of the ovariectomized mouse, rat, and guinea-pig 

 with oestrin leads to growth of the vaginal mucosa, which ends in 

 the keratinization and sloughing off of the surface layers. In 

 the uterus, typical cestrous changes are also produced, including, 

 in the mouse and rat, the characteristic distension of the lumen 

 and attenuation of the uterine wall. The reactions of these 

 animals have been observed by a large number of workers and 

 are beyond dispute. The administration of excessive doses leads 

 to an exaggeration of the oestrous symptoms analogous with 

 that found in nymphomania. Other animals in which the 

 action of oestrin has been tested after ovariectomy include the 

 opossum and Macacus rhesus. 



In view of these reactions of test animals there can be no 

 doubt whatever that oestrin is responsible for the extra-ovarian 

 changes typical of prooestrus and oestrus. The actual 

 mechanism of its growth-promoting action in the organs is not 

 known. 



(b) ACTION ON NORMAL ANIMALS 



The injection of oestrin into the normal animal just before 

 oestrus is due, leads to an intensification of the normal changes 

 in the accessory organs without alteration of the ovarian cycle 



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