C. R. AUSTIN AND M. W. H. BISHOP 75 



Transport and Distribution of Spermatozoa 



Motility is an almost miiversal characteristic of male gametes 

 throughout the animal kingdom and it undoubtedly facilitates 

 the meeting of egg and spermatozoon. However, the available 

 evidence, particularly that relating to rate of transport of sperma- 

 tozoa in the female tract, indicates that during their passage 

 from the site of deposition to the site of fertilization the sperma- 

 tozoa play a passive role in most species and transport depends 

 little upon their active swimming. 



The importance of muscular activity of the female tract in the 

 transport of spermatozoa has been appreciated for a long time. 

 Heape (1898) imputed this significance to the activity of the 

 dog uterus which he found to be increased by stimulation of the 

 external genitalia. Westman (1926) observed augmented con- 

 tractions of the Fallopian tubes of female rabbits when in the 

 presence of the male, and Krehbiel and Carstens (1939) found 

 that fluids placed in the rabbit vagina were carried throughout 

 the uterus when the vulva was artificially stimulated. Increased 

 uterine activity in the rabbit following mating was noted by 

 Reynolds (1930), and Van Demark and Hays (1951, 1952, 1953) 

 have shown that strong uterine contractions in the cow are in- 

 duced by various mating stimuli, including the sight of the male, 

 although coitus was the most effective. Hays and Van Demark 

 (1952) claim that rapid spermatozoon transport occurs in the 

 perfused, excised cow uterus, provided that oxytocin is present 

 in the perfusate. It has been shown in the mare (Millar, 1952) 

 that the orgasm of coitus produces a negative pressure within 

 the uterus which would have the effect of rapidly drawing the 

 semen into the uterine lumen. 



Both the act of ejaculation and the physical and chemical 

 properties of the seminal plasma may also assist transport. In 

 the rodents, the sow, and the mare, the spermatozoa are not de- 

 posited in the vagina but passed directly through the cervix. 

 Gelation of the semen of the boar and stallion presumably plays 

 an important role in retaining the large ejaculate in the uterus. 



