198 TRANSPORTATION OF THE GAMETES 



survival is probably not longer than 1 to 3 days. In the rabbit, sperm are in 

 the female genital tract about 10 to 14 hours before fertilization normally 

 occurs; they lose their ability to fertilize during the early part of the second 

 day (Hammond and Asdell, '26). In the genital tract of the female rat, sperm 

 retain their motility during the first 17 hours but, when injected into the 

 guinea pig uterus, they remain motile for only four and one-half hours. How- 

 ever, guinea-pig sperm will remain alive for at least 41 hours in the guinea- 

 pig uterine horns and Fallopian tubes (Yochem, '29). 



E. Sperm Survival Outside the Male and Female Tracts 



1. In Watery Solutions Under Spawning Conditions 

 In watery solutions in which the natural spawning phenomena occur, the 

 life of the sperm is of short duration. The sperm of the frog, Rana pipiens, 

 may live for an hour or two, while the sperm of Funduliis heteroclitiis probably 

 live 10 minutes or a little longer. In some other teleost fishes, the fertilizing 

 abihty is retained only for a few seconds. 



2. Sperm Survival Under Various Artificial Conditions; 

 Practical Application in Animal Breeding 



One of the main requisites for the survival of mammalian and bird sperm 

 outside the male or female tract is a lowered temperature. The relatively high 

 temperature of 45 to 50° C. injures and kills mammalian sperm while body 

 temperatures are most favorable for motility of mammalian and bird sperm; 

 lower temperatures reduce motility and prolong their life. Several workers 

 have used temperatures of to 2° C. to preserve the life of mammalian and 

 fowl sperm, but a temperature of about 8 to 12° C. is now commonly used 

 in keeping mammalian and fowl sperm for purposes of artificial insemination. 

 Slow freezing is detrimental to sperm, but quick freezing in liquid nitrogen 

 permits sperm survival even at a temperature of — 195° C. (See Shettles, '40; 

 Hoaglund and Pincus, '42.) 



Another requirement for sperm survival outside the genital tract of the 

 male is an appropriate nutritive medium. Sperm ejaculates used in artificial 

 insemination generally are diluted in a nutritive diluent. The following diluent 

 (Perry and Bartlett, '39) has been used extensively in inseminating dairy 

 cattle: 



Na,SO, 1.36 gr. ) 



Dextrose 1.20 gr. [ per 100 ml. H,,0. 



Peptone 0.50 gr. ) 



Also, a glucose-sahne diluent has been used with success (Hartman, '39, 

 p. 685). Its composition is as follows: 



Glucose 30.9 gr. \ 



Na HP0,I2H,0 6.0 gr. I ,^^^ ^, ^.,0. 



NaCl 2.0 gr. ( 



KH.PO, 0.1 gr. ; 



