BIOLOGY OF EGGS AND IMPLANTATION 



821 



movement of these fluids into the oviduct 

 (Fischel, 1914). However, observations on 

 normal fluid flow within the periovarial sac 

 are very limited. It has been demonstrated 

 that if dyes such as Janus green or particu- 

 late material are introduced into the perio- 

 varial space in the immediate vicinity of the 

 ostium, the material quickly passes into the 

 first loop of the oviduct (Alden, 1942b). 

 Transport is effected primarily by the cili- 

 ary activity of the fimbriated end of the 

 ostium (Clewe and Mastroianni, 1958) . Fur- 

 thermore, if newly ovulated eggs are placed 

 on the surfaces of the fimbriae in the rat, 

 mouse, or hamster the cilia will sweep them 

 into the infundibulum within 8 seconds 

 (Blandau, unpublished observations). How 

 those ova located at some distance from the 

 oviduct reach the fimbria has not been ob- 

 served. 



Under normal physiologic conditions the 

 ovary moves backwards and forwards 

 within the periovarial sac. These movements 

 are accentuated at the time of ovulation 

 and are effected by the abundant smooth 

 muscle in the mesovarium. Such activity 

 keeps the fluids of the periovarial sac in 

 motion. Those eggs ovulated at the opposite 

 side of the ovary away from the infundibu- 

 lum are passively moved into its vicinity 

 where ciliary currents then aid in complet- 

 ing transport. 



A potentially wide communication be- 

 tween the ostium of the oviduct and the 

 peritoneal cavity exists in a variety of ani- 

 mals such as the guinea pig, rabbit, monkey, 

 and man (Sobotta, 1917; Westman, 1952). 

 The extent of the communication varies 

 with the stage of the menstrual or estrous 

 cycle. Ordinarily in a rabbit not in heat, the 

 fiml)riae do not cover the ovary. As the time 

 of ovulation approaches, there is a great in- 

 crease in motility and turgidity of the fim- 

 briae so that they almost enclose the ovary 

 (Westman, 1926, 1952). Recently attempts 

 have been made to observe the activities of 

 the human fimbriae by means of abdominal 

 l)eritoneoscopy or exploratory culdotomy. 

 Elert (1947) has seen the elongated fimbria 

 grasp the lower pole of an ovary for as long 

 as 2 minutes. Doyle (.1951, 1954), how^ever, 

 failed to observe either a sweeping or grasp- 

 ing motion of the fimbriae before or during 



the rupture of the follicle. He suggests that 

 in the human female the initial transport of 

 the ovum is by a process in which it floats 

 into the cul-de-sac and from there is si- 

 phoned into the ampulla by simple peristal- 

 tic contractions which originate at the re- 

 gion of the fimbriae. Doyle's (1956) recent 

 observations are more in line with those de- 

 scribed by Elert above. 



It has been suggested that the activity of 

 the abundant smooth musculature of the 

 adnexa and the fimbriae produces a power- 

 ful suction effect on the ovary, thus drawing 

 the ovulated eggs into the tube (Sobotta, 

 1917; Westman, 1952). It is a fact, however, 

 that no one has made measurements of this 

 presumed negative pressure, nor, as pointed 

 out earlier, has anyone observed a newly 

 ovulated mammalian ovum transported 

 from the surface of the ovary into the ovi- 

 duct in animals in which the ovaries are not 

 enclosed in periovarial sacs. During lapa- 

 rotomy there are very real problems in 

 maintaining the normal anatomic position 

 and physiologic condition of the oviducts 

 so that their actual function in vivo can be 

 assessed accurately. In general the muscu- 

 lar activity of the fimbriae has received 

 more enthusiastic support than the cilia as 

 being the agent for the transport of eggs 

 from ovary to oviduct. However, in the few 

 instances in which eggs were placed close to 

 the fimbriae and egg transport observed di- 

 rectly, the ciliary activity of the fimbriae 

 appeared to be primarily responsible. 



The rate of the ciliary beat in the rabbit 

 Fallopian tubes has been studied by Borell, 

 Nilsson and W^estman (1957) ; during estrus 

 the cilia beat at a rate of 1500 beats per 

 minute. 



The rate increases about 20 per cent on 

 the 2nd and 3rd day after copulation and at 

 the time of implantation. By the 14th day 

 of pregnancy the rate of beat had returned 

 to normal. There was no significant differ- 

 ence in the rate of beat in cilia removed 

 from various segments of the oviduct. Many 

 more direct and continuous observations on 

 the intact oviducts of different animals are 

 needed before definite conclusions may be 

 reached as to the mechanics of egg trans- 

 port from the ovary to the infundibulum. 



In the rat, mouse, and hamster, one of the 



