HUMAN PREGNANCY TESTS 



23 



Pituitary secretion 



LH(ICSH) 



growth of corpu 

 luteum 



degeneration of 

 corpus luteum 



FSH 



growth of follicle- 



rupture of follicle 



(ovulation) 

 estrone liberated 

 into blood stream 



this is another story (see Chap. 18). Whatever the exact relationship, there 

 is certainly a reciprocal relationship between the pituitary and the ovary, each 

 exerting a control over the other to form a rhythmic cycle. 



Human pregnancy tests 



These studies on the control of ovulation have resulted in some practical 

 applications. In the first place, we find that hormones other than those of the 

 pituitary will stimulate the ovaries and that some of these substances will cause 

 ovulation. And in particular, during early human pregnancy, a hormone 

 appears in the urine which, when injected into immature mice, will stimulate 

 the ovaries of the mice to mature. This gonadotropic hormone has been traced 

 to the chorion formed by the developing embryo. The injection of urine into 

 an immature animal thus becomes a test for pregnancy and, in its original 

 form, is known as the Aschheim-Zondek test. There is a modification of the 

 test in which rabbits are used; this is called the Friedman test. 



Since a reaction to gonadotropic hormones is a general one, other animals 

 may be used for testing pregnancy. Some biologists have attempted to use 

 the South African frog, which lays its eggs when exposed to pregnancy urine. 

 Male frogs also react by releasing sperm. There have also been some tests 

 devised in which fish are used; indeed any number of animals could be em- 

 ployed to test for the presence of this pregnancy hormone. Because the human 



