THE HORMONES IN HUMAN REPRODUCTION 



PHENANTHRENE 



With one more ring, this time of 6 carbons instead of 6, we get 

 cyclo-penteno-phenanthrene : 



CYCLOPENTENOPHENANTHRENE 



This structure of 4 rings, two upstairs and two downstairs, 

 has a great significance to the chemist and physiologist, for 

 it is the basis of many important substances in the body. 

 When the rings are unsaturated at various linkages and pro- 

 vided with various side groups and side chains, an enormous 

 series of compounds occurs, which are known as steroids. 

 These include the sterols (one of which, cholesterol, is a wide- 

 spread constituent of the animal body), the bile acids, and 

 the sex gland hormones. The unravelling of their constitution 

 has been one of the great feats of modern organic chemistry, 

 and it is now being followed up by the rapid production of 



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