SPERM SURVIVAL IN FEMALE GENITAL TRACT 197 



if this method fails or is weakened, sperm motility itself comes to the rescue, 

 and sperm are transported under their own power. 



In view of the above-mentioned behavior of the oviduct in transporting 

 sperm, it is important to observe that the estrogenic hormone is in a large 

 way responsible for the activities of the oviduct during the early phases of 

 the reproductive period and, consequently, influences the conditions necessary 

 for sperm transport. It enhances this process by arousing a state of irritability 

 and reactivity within the musculature of the uterus and the Fallopian tubes. 

 It also induces environmental conditions which are favorable for sperm sur- 

 vival within the female genital tract. 



3) When Fertilization Occurs in the Ovary. In certain viviparous fishes 

 the egg is fertilized in the ovary (e.g., Gambusia affinis; Heterandria formosa). 

 (See Turner, '37, '40; Scrimshaw, '44.) As the sperm survive for months in 

 the female tract, sperm transport is due probably to the movements of the 

 sperm themselves. Motility evidently is a factor in the case of the eutherian 

 mammal, Ericidus, where ovarian fertilization presumably occurs according to 

 Strauss, '39. 



D. Sperm Survival in the Female Genital Tract 



The length of life of sperm in the female genital tract varies considerably 

 in different vertebrates. In the common dogfish, Squalus acanthias, and also 

 in other elasmobranch fishes, sperm evidently live within the female genital 

 tract for several months, and retain, meanwhile, their ability to fertilize. In 

 the ordinary aquarium fish, the guppy (Lebistes), sperm may live for about 

 one year in the female tract (Purser, '37). A long sperm survival is true also 

 of the "mosquito fish," Gambusia. Within the cloacal spermatheca of certain 

 urodele amphibia, sperm survive for several months. Within the uterus of the 

 garter snake they may live for three or more months (Rahn, '40), while in 

 the turtle, Malaclemys centrata, a small percentage of fertile eggs (3.7 per 

 cent) were obtained from females after four years of isolation from the male 

 (Hildebrand, '29). Sperm, within the female tract of the hen, are known to 

 Hve and retain their fertility for two or three weeks or even longer (Dunn, '27 ) . 

 In the duck the duration of sperm survival is much shorter (Hammond and 

 Asdell, '26). 



Among mammals, the female bat probably has the honor of retaining 

 viable sperm in the genital tract for the longest period of time, for, while the 

 female is in hibernation, sperm continue to live and retain their fertilizing 

 power from the middle of autumn to early spring (Hartman, '33; Wimsatt, 

 '44). According to Hill and O'Donoghue ('13) sperm can remain alive within 

 the Fallopian tubes of the Australian native cat, Dasyurus viverrinus, for "at 

 least two weeks." However, it is problematical whether such sperm are capable 

 of fertilizing the egg, for motility is not the only faculty necessary in the 

 fertilization process. In most mammals, including the human female, sperm 



