200 TRANSPORTATION OF THE GAMETES 



inactive; but an examination shortly after laying reveals the fact that the oviduct 

 is in a state of high excitability, with the infundibulum usually clasping an ovum 

 in the follicle. In one case it was embracing a follicle containing a half-developed 

 ovum, and with such tenacity that a considerable pull was necessary to disengage 

 it. It seems certain, therefore, that the stimulus which sets off the mechanism for 

 ovulation is not received until the time of laying, or shortly after. 



If the egg falls into the ovarian pocket (i.e., the space formed around the 

 ovary by the contiguous body organs), the infundibulum still is able to engulf 

 the egg. Relative to the engulfment of an egg lying within the ovarian pocket, 

 Romanoff and Romanoff, '49, p. 215, states: 



The infundibulum continues to advance, swallow, and retreat, partially engulfing 

 the ovum, then releasing it. This activity may continue for half an hour before the 

 ovum is entirely within the oviduct. 



b. Mammals 



In those mammals in which the ovary lies free and separated from the 

 mouth of the oviduct (figs. 29, 111) it is probable that the infundibulum 

 moves over and around the ovary intermittently during the ovulatory period. 

 Also, the ovary itself changes position at the time when ovulation occurs, 

 with the result that the ovary moves in and out of the infundibular opening 

 of the uterine tube (Hartman, '39, p. 664). In the Monotremata (prototherian 

 mammals) during the breeding season, the enlarged membranous funnel 

 (infundibulum) of the oviduct engulfs the ovary, and a thick mucous-like 

 fluid lies in the area between the ovary and the funnel (Flynn and Hill, '39). 

 At ovulation the relatively large egg passes into this fluid and then into the 

 Fallopian tube. In the rat and the mouse which have a relatively closed ovarian 

 sac, the bursa ovarica, around the ovary (figs. 37, 112) contractions of the 

 Fallopian tube similar to those of other mammals tend to move the fluid and 

 contained eggs away from the ovary and into the tube. Thus it appears that 

 the activities of the mouth and upper portions of the oviduct serve to move 

 the egg from the ovarian surface into the reproductive duct at the time of 

 ovulation in the mammal and bird. This method of transport probably is present 

 also in reptiles and elasmobranch fishes. In the mammal this activity has been 

 shown to be the greatest at the time of estrus. The estrogenic hormone, there- 

 fore, is directly involved in those processes which transport the egg from the 

 ovary into the uterine tube. 



In women, and as shown experimentally in other mammals, the removal 

 of the ovary of one side and the ligation or removal of the Fallopian tube on 

 the other side does not exclude pregnancy. In these cases, there is a transmi- 

 gration of the egg from the ovary on one side across the peritoneal cavity to 

 the opening of the Fallopian tube on the other where fertilization occurs. 

 This transmigration is effected, presumably, by the activities of the intact 

 infundibulum and Fallopian tube of the contralateral side. 



Another aspect of egg transport in the mammal is the activity of the ciHa 



