REPRODUCTION 27 



Some of the domestic animals do not come in heat 

 while suckling young, while others discharge eggs and 

 undergo the periodical phenomenon of heat as readily 

 during lactation as at any other time. 



27. The Fallopian tubes. The egg which has been 

 discharged as the result of the processes described above 

 finds its way to the uterus through the Fallopian tubes 

 in mammals or the oviduct in birds. These are small, 

 very crooked canals leading from the ovary to the uterus. 

 This accessory organ is not rigidly joined to the ovary 

 by tissues, but the end nearest the ovary is mostly free 

 to move to different sides of the ovary. The ovarian 

 end of the Fallopian tube is expanded into a fimbriated 

 extension which spreads out not unlike the fingers of the 

 hand. The comparison will be still more exact if we con- 

 ceive of the fingers of the hand as being connected by 

 web-like tissues. 



In many mammals, the tube is lined with cilia which 

 move from the ovary toward the uterus. In normal 

 cases when the egg is discharged from the ovary, the 

 fimbriated expansion of the Fallopian tube clasps the 

 ovary at the point where the Graafian follicle bursts 

 through its walls. The ciliary movement within the tube, 

 assisted by muscular movements of the tube itself, carries 

 the egg from the ovary to the uterus. The time required 

 for the passage of the egg through the Fallopian tube has 

 not been definitely determined for all mammals, but is 

 known to vary from three to eight days. 



The union of the spermatozoon and the egg usually 

 takes place in the Fallopian tube. To accomplish this 

 union, it is necessary for the sperm-cell to pass into the 

 uterus and up into the tube. This it is able to do by 

 reason of its possessing the power of independent motion. 



