314 NORMAL HISTOLOGY AND ORGANOGRAPHY. 



tremity. The isthmus is smooth and round, about 

 one inch in length, and opens into the fundus of the 

 uterus by a small orifice that will barely admit an 

 ordinary bristle. It is a straight and narrow part of 

 the duct, about 2 to 3 mm. in diameter. The am- 

 pulla encircles the ovary and is at least twice the size 

 of the isthmus. It is also less firm to the touch, 



Fig. 228. Cross section of ampulla of Fallopian tube. 



being flabby while the isthmus is cord-like. The 

 neck is an annular constriction between the ampulla 

 and fimbriated extremity, the latter being a funnel- 

 shaped expansion of the ovarian end of the tube, 

 which terminates in a number of irregular processes 

 called fimbria. The fimbriae vary considerably in 

 size and number. Many of them are branched, and 



