TRANSPORTATION OF EGG FROM OVARY TO SITE OF FERTILIZATION 201 



lining the fimbriae, mouth, and to a great extent, the ampullary portions of 

 the uterine (Fallopian) tube itself. The beating of these cilia tend to sweep 

 small objects downward into the Fallopian tube. However, these activities 

 are relatively uninfluential in comparison to the muscular activities of the 

 infundibulum and other portions of the Fallopian tube. 



Egg transport between the ovary and the oviduct is not always as efficient 

 as the above descriptions may imply. For, under abnormal conditions the 

 egg "may lose its way" and if fertilized, may begin its development within' 

 the spacious area of the peritoneal cavity. This sort of occurrence is called 

 an ectopic pregnancy. In the hen, also, some eggs never reach the oviduct 

 and are resorbed in the peritoneal cavity. 



3. Transportation of the Egg in Those Species Where 



Fertilization is Effected in the Caudal Portion 



OF the Oviduct or in the External Medium 



a. Frog 



In the adult female of the frog (but not in the immature female or in the 

 male) cilia are found upon the peritoneal lining cells of the body wall, the 

 lateral aspect of the ovarian ligaments, the peritoneal wall of the pericardial 

 cavity and upon the visceral peritoneum of the liver. Cilia are not found on 

 the coelomic epithelium supporting and surrounding the digestive tract, nor 

 are they found upon the epithelial covering of the ovary, kidney, lung, bladder, 

 etc. (fig. 113). (See Rugh, '35.) This ciliated area has been shown to be 

 capable of transporting the eggs from the ovary anteriad to the opening of 

 the oviduct on either side of the heart (fig. 113) (Rugh, '35). In this form, 

 therefore, ciliary action is the main propagating force which transports the 

 egg (external migration) from the ovary to the oviduct. Internal migration 

 of the egg (transportation of the egg within the oviduct) also is effected mainly 

 by cilia in the common frog, although the lower third of the oviduct "is abun- 

 dantly supplied with smooth muscle fibers," and "shows some signs of peri- 

 stalsis" (Rugh, '35). The passage downward through the oviduct to the uterus 

 consumes about two hours at 22° C. and, during this transit, the jelly coats 

 are deposited around the vitelline membrane. The jelly forming "the innermost 

 layer" is deposited "in the upper third of the oviduct, and the outermost layer 

 just above the region of the uterus." The ciliated epithelium, due to the spiral 

 arrangement of the glandular cells along the oviduct, rotates the egg in a spiral 

 manner as it is propelled posteriad (Rugh, '35). Once within the uterus, the 

 eggs are stored for various periods of time, depending upon the temperature. 

 During amplexus, contractions of the uterine wall together, possibly, with 

 contractions of the musculature of the abdominal wall, expel the eggs to the 

 outside. At the same time, the male frog, as in the toad, discharges sperm 

 into the water over the eggs (fig. 103). In the toad, the eggs pass continu- 



