972 



SPERM, OVA, AND PREGNANCY 



1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 

 Weeks of pregnancy 



Fig. 16.11. The con«?ntiation of progesterone in the ovarian venous blood of the preg- 

 nant ewe. Progesterone was determined by chemical methods. (From D. G. Edgar and 

 J. W. Ronaldson, J. Endocrinol., 16, 378, 1958.) 



0.0098 ixg. per ml. plasma. It is of interest 

 that the level remained constant from the 

 32nd to about the 256th day of pregnancy 

 and then decreased several days before 

 parturition. In the human being values of 

 0.17 to 0.44 fig. per ml. during the final tri- 

 mester of pregnancy have recently been 

 reported (Oertel, Weiss and Eik-Nes ( 1959 ) . 

 Numerous investigators have suggested 

 that the discrepancy between the chemical 

 and biologic assays is due to the presence 

 of unknown gestagens in the blood. This 

 has been validated in part by the discovery 

 of 2 metabolites in the blood of the preg- 

 nant human female (Zander, Forbes, Neher 

 and Desaulles, 1957). They have been iden- 

 tified as 20a-hydroxypregn-4-en-3-one and 

 20^-hydroxypregn-4-en-3-one and have 

 been shown to be active in both the Clau- 

 berg and Hooker-Forbes tests (Zander, 

 Forbes, von IMiinstermann and Neher 

 1958 ) . The 20/?-epimer was twice as active 

 as progesterone in the Hooker-Forbes test 

 and the 20a-epimer one-fifth as active. It 



is likely that more unidentified gestagens 

 occur in the blood and other tissues. 



C. SOURCES OF GESTAGENS 



The second question asked above con- 

 cerning the role of the placenta versus the 

 ovary as a source of progesterone probably 

 cannot be answered in a simple manner. 

 Wide differences exist between species (1) 

 in the need of the ovary for maintenance 

 of pregnancy, (2) in the concentration of 

 the hormone in peripheral blood, (3) in the 

 activity of the placenta in secreting pro- 

 gesterone, and (4) in the presence of extra- 

 ovarian and extraplacental sources of the 

 hormone. 



The presence of progesterone in the pla- 

 centa of the human being has been con- 

 firmed (Salhanick, Noall, Zarrow and Sam- 

 uels, 1952; Pearlman and Cerceo, 1952) 

 and a high output of progesterone demon- 

 strated. Zander and von ]\Iiinstermann 

 (1956) and Pearlman (1957) independently 



