APPENDIX II 



tion that the coiling of the arteries is essential to menstrua- 

 tion. In a pending article, a fellow-worker of the author, Dr. 

 Irwin H. Kaiser, shows that the corresponding arteries in 

 certain New World monkeys that undergo at least a rudi- 

 mentary type of menstruation, are not coiled. Some, more- 

 over, of the current hypotheses about the structure and func- 

 tion of the arteries in women and in Rhesus monkeys, to be 

 mentioned in Note 13, do not depend upon the coiling. 



The reader should therefore substitute for the statement 

 in our text that "menstruation is primarily an affair of the 

 coiled arteries" the more cautious and less specific thought 

 that menstruation is primarily dependent upon special 

 peculiarities of the arterial circulation of the endometrium, 

 meanwhile keeping his mind open until this fascinating 

 problem is further elucidated. 



Note 13 (page 170, line 21). Current thought about the 

 mechanism of menstruation. The hypotheses set forth in the 

 original edition of this book may still be read profitably, 

 except that the reader should substitute the term "endo- 

 metrial arteries" for "coiled arteries" because (as explained 

 in Note 12) there is evidence that the coiling is not per se es- 

 sential to the menstrual process. The whole subject of the 

 cause of menstruation has been actively revived in 1946-194!'7, 

 largely as the result of studies made in Copenhagen by a 

 group of anatomists and pathologists who did not let the 

 German occupation stop their research. 



Most of the thinking still involves the idea that the periodic 

 menstrual flow results from some peculiarity or other of the 

 endometrial arteries which makes them dependent upon 

 hormonal support. As already mentioned, a view now some- 

 what in disfavor held that it is the coiling of these arteries 

 which renders them sensitive to fluctuation of the ovarian 

 hormones. It was conjectured that as the endometrium grows 

 thicker in each cycle under the influence of estrogen, the 

 coiling becomes more intense until the flow of arterial blood 



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