A HORMONE FOR GESTATION 



not perfectly convincing, although we know now their out- 

 come was correct. Fraenkel returned to his laboratory and 

 after seven years was able to present in 1910 completely 

 acceptable results. 



At about the same time as these later experiments, and 

 apparently without knowledge of Fraenkel's work, the 

 French histologist Bouin and his colleague Ancel had under 

 way experiments (published in 1910) which demonstrated 

 another aspect of the activity of the corpus luteum. They 

 found that during early pregnancy the lining of the uterus 

 undergoes a remarkable change. This is shown in Plate 

 XVII, B, which reproduces one of Ancel and Bouin's actual 

 figures.^ The tubular glands of the uterus begin to grow 

 longer, to secrete fluid and therefore to become dilated. Their 

 cells multiply so fast that there is no longer enough room for 

 them in the simple tubular wall, and the glands begin to 

 become folded or pleated. The folds of the endometrium are 

 deeply pervaded by these glands ; and finally in a section of 

 the uterus one sees a beautiful lacelike pattern (Plate XVII, 

 B, right) representing the cross-section of this gland-filled 

 tissue. 



This change in the condition of the lining of the uterus, 

 described by Ancel and Bouin, gave the key to the discovery 

 of the corpus luteum hormone. We shall have to mention it 

 again and again. W^e can therefore save words by using the 

 technical name of this change, i.e. progestational prolifera- 

 tion, that is to say "growth and change which favors gesta- 

 tion." Obviously, as the picture shows, it is growth and 

 change; that it favors gestation will be proved as we go 

 along. 



Anticipating our story again, so that we may be perfectly 

 clear about this important matter, let it be said that proges- 

 tational proliferation does not occur in the rabbit only, but 



1 Photographs of the rabbit's uterus magnified, shown in this book, 

 represent sections (slices) across the uterus, as one slices a banana. 



{ 107 } 



