THE PITUITARY BODY 



is greatest just before parturition. If the corpora lutea are 

 removed during the first part of pregnancy, the uterus be- 

 comes oxytocin-sensitive after about lo hours (Knaus, 1927- 

 28, 1930; Robson, 1933). 



If pseudopregnant proliferation of the rabbit's uterus has 

 been provoked by the injection of anterior-lobe extract (so 

 that corpora lutea are formed in the ovaries) or by corpus 

 luteum extract, oxytocin-insensitivity may also be observed 

 (Robson, 1932; and others). Not infrequently, however, a 

 pseudopregnant uterus may be oxytocin-sensitive. There- 

 fore, it has been suggested that the loss of the uterine re- 

 sponse to the oxytocic principle is due to some substance 

 other than progesterone (Hartmann and Storring, 1931; 

 Robson and Illingworth, 1931; and Robson, 1932; see also 

 Siegmund, 1930). 



Assuming that the human uterus exhibits similar changes 

 in response in relation to secretory activity by the corpus 

 luteum, Knaus (1929-30) made records of the intra-uterine 

 pressure of women to whom he also gave o. i cc. of a pos- 

 terior-lobe extract intravenously. He concluded that the ef- 

 fect of the extract disappeared about the ninth day before 

 menstruation and was slight or absent thereafter. This 

 change he attributed to the secretion of the corpus luteum of 

 ovulation; he estimated that ovulation occurred on the 

 fourteenth to sixteenth day. Wittenbeck's general results 

 (1930) confirmed those of Knaus although in one patient a 

 positive oxytocin response was obtained despite the presence 

 of a corpus luteum. Quite the opposite results were obtained 

 by Schultze (1931) and Tachezy (1934). These authors con- 

 cluded that the uterine response to the oxytocic principle is 

 greatest after the sixteenth day of the menstrual cycle. The 

 intact pregnant human uterus (2-5 months) responded to 

 the oxytocic principle in seven of eight patients (Wittenbeck, 

 1930; Tachezy, 1934). Robson (1933) studied the response of 



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