THE HORMONES IN HUMAN REPRODUCTION 



of moisture between the smooth surfaces of the organs in the 

 region of the ovary. The open funnel of the oviduct is directly 

 at hand, and moreover the moisture in which the egg drifts is 

 constantly drawn into the oviducts, carrying the egg with it, 

 by action of the cilia mentioned above. Small particles of 

 carmine or even foreign eggs, introduced into the lower ab- 

 dominal cavity by the experimenter, are within a few hours 

 carried down the oviducts toward the uterus. 



It is even possible for the egg to drift across from one ovary 

 to the opposite oviduct, a distance of roughly 3 or 4 centi- 

 meters (1 to 2 inches), and therefore a woman who has had 

 one ovary and the opposite Fallopian tube removed is not 

 necessarily sterile. In some animals, e.g. the sow, the oviduct 

 expands into a voluminous sac partly enclosing the ovary; 

 in the dog and cat the enclosure is almost complete; in the 

 rat and mouse it is quite complete and eggs are obliged to 

 travel down the oviduct corresponding to the ovary from 

 which they came. 



How are the eggs transported? We know that this trumpet- 

 like capsular part of the oviduct, just mentioned, throws 

 itself during life into squirming movements which are espe- 

 cially active at the time the eggs are discharged. This may 

 help draw the eggs into the oviduct. How they are pushed 

 along toward the uterus, once they are in the tubular canal 

 of the oviduct, is at present under discussion. When there are 

 several eggs (that is, in animals which bear several young at 

 a time) the eggs travel together at first, sticking together in 

 a little web of cellular debris they have brought with them 

 from the ovary, but after a few hours this entanglement dis- 

 solves and the eggs travel free and bare, though still more 

 or less closely together. As will be seen from Plate X, C, Dy 

 the lining of the tubes forms voluminous folds, so that the 

 available space is hardly larger than necessary to permit 

 passage of the eggs. It used to be thought without question 

 that the eggs are brushed along by action of the lashlike cilia 



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