THE HORMONES IN HUMAN REPRODUCTION 



Graaf in 1672. A French medical student who wrote a thesis 

 about them in 1909 listed twenty-five different incorrect 

 hypotheses about their function; but already in 1898 Louis- 

 Auguste Prcnant had suggested that they might be glands 

 of internal secretion, making some sort of hormone for the 

 benefit of the eggs with which they are associated. Now that 

 we know more about such glands, any microscopist can see 

 that the corpora lutea have the signs of endocrine function 

 written all over them. The large, imposing cells, built into a 

 mass that communicates with the rest of the body only by 

 the blood vessels ; the delicate texture, scarcely supported by 

 connective tissue; the wealth of blood supply that reaches 

 every cell — these are the telltale evidences that the corpora 

 lutea are indeed organs of internal secretion, and that what- 

 ever product they secrete must be poured into the blood and 

 carried away to exert its effect upon some other organ. The 

 full story of the corpus luteum hormone, as we know it now, 

 will be told in Chapter V. 



The life of the corpus luteum is relatively short. If the egg 

 is fertilized, the corresponding corpus luteum persists through 

 the greater part, if not all, of pregnancy. If the egg is not 

 fertilized, the corpus luteum has an active life of only about 

 two weeks before it begins to degenerate. In the human cycle 

 of four weeks a fresh corpus luteum is present, therefore, 

 about half the time. The older corpora are visible in various 

 stages of degeneration. Five or six months after the formation 

 of a corpus luteum all traces of it have disappeared. 



The oviducts. When an egg is discharged from the ovary, 



Plate IX. The corpus luteum of the Rhesus monkey. A, ovary split inty 

 two parts and laid open to show the corpus luteum. Magnified 4 times. Courtesy 

 of C. G. Hartman. B, section through ovary showing a large corpus luteum 

 (Corner collection, no. 187). Magnified 10 times. C, small part of corpus luteum, 

 magnified 250 times to show the cells. The narrow clear spaces between the 

 cells, bordered by small dark nuclei, are capillary blood vessels. At the \ef-t 

 6 cells and parts of a blood capillary have been outlined with ink to show 

 how each cell is in contact with a blood vessel. 



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