730 



SPERM, OVA, AND PREGNANCY 



of insemination to the site of fertilization or 

 to intermediate levels of the reproductive 

 system. Thus, for example, the mean velocity 

 of bull sperm is on the order of 100 /x per sec. 

 (Moeller and VanDemark, 1955; Gray, 

 1958 ) , and if a straight path were followed, 

 it would require about IV2 hours for the 

 gametes to cover the entire length of the 

 tract; actually the time required after nat- 

 ural mating is less than 2V2 minutes (Van- 

 Demark and Moeller, 1951). 



Rapid sperm migration through the uterus 

 was first demonstrated by Hartman and Ball 

 (1930) in the rat; within 2 minutes after 

 copulation myriads of sperm had entered 

 the tubes (Table 13.6 ) . A subsequent investi- 

 gation showed that a few sperm were present 

 at the periovarial sac within IVk minutes 

 after copulation (Warren, 1938). Blandau 

 and Money (1944) later indicated that at 

 copulation, rat sperm are catapulted through 

 the cervix into the uterine cornua, and within 

 15 minutes have entered the Falloi^an tubes 

 in considerable numbers. By clamping the 

 middle of the tubes at various times after 

 copulation, the distribution of sperm could 

 be determined. After 15 minutes, sperm were 

 found in 42 per cent of the uterine (lower) 

 segments of the oviducts examined and 21 

 per cent of the ovarian (upper) segments; 

 after 30 minutes, 85 per cent and 62 per cent, 

 respectively; after 45 minutes, 90 per cent 

 and 96 per cent; and at 60 minutes, both the 

 uterine and ovarian portions of oviducts of 

 all animals studied contained sperm. 



After insemination of the mouse, sperm 

 reach the tubal infundibulum, the site of 

 fertilization, within 15 minutes (Lewis and 

 Wright, 1935). In the bitch, 20 minutes or 



TABLE 13.6 



Time of passage of rat spermatozoa into 



female genital tract 



(From C. G. Hartman and J. Ball, Proc. Soc. 



Exper. Biol. & Med., 28, 312-314, 1930.) 



less are required (Evans, 1933; Whitney, 

 1937), and in the hamster about 30 minutes 

 (Chang and Sheaffer, 1957). Rubenstein, 

 Strauss, Lazarus and Hankin (1951) claimed 

 that human sperm deposited at the cervix 

 just before hysterectomy, can be recovered 

 from the Fallopian tube 30 minutes later ; the 

 nature of the operation, however, might se- 

 riously affect the rate of transport. Other re- 

 ports of sperm-transport time in women 

 range up to 3 hours (Chang and Pincus, 

 19511. 



As part of a series of marvelously planned 

 and executed experiments on cattle, Van- 

 Demark and co-workers have shown that 

 sperm migration requires only 2 to 4 minutes 

 whether the heifers are mated or artificially 

 inseminated. Indeed, even dead sperm, after 

 artificial insemination, were transported to 

 the uj^pcr reaches of the oviduct within 4.3 

 minutes (VanDemark and Moeller, 1951). 

 Sperm-migration times reported for the ewe 

 have varied considerably, ranging from sev- 

 eral hours (Green and Winters, 1935) down 

 to 6 to 16 minutes (Starke, 1949; Schott and 

 Phillips, 1941). This variation is to be ac- 

 counted for less by changes dependent on the 

 estrous cycle (Dauzier and Wintenberger, 

 1952) than by improvements in technique. 



The rabbit, in many ways a domestic 

 anomaly in reproductive matters, appar- 

 ently requii-es several hours for transport of 

 a significant number of sperm, although the 

 "vanguard" may reach the ampulla within 

 an hour after insemination (Chang, 1952; 

 Adams, 1956). Heape's demonstration in 

 1905 of approximately 4 hours for migration 

 seems to have stood the test of time. On the 

 basis of recovery of spermatozoa from sepa- 

 rate segments of the genital tract, Parker 

 (1931) andBraden (1953) found that 2.5 to 

 3 hours are required for transport. Confirma- 

 tion is afforded by experiments involving 

 ligation of the tubes at various intervals 

 after copulation (Adams, 1956; Gr,'enwald, 

 1956) ; whereas some eggs are fertilized when 

 the tubal blocks are made prior to 2.5 hours, 

 ligations made 3 to 5 hours after copulation 

 do not prevent a high percentage of fertility. 

 Whether this order of transport time is an 

 adaptation to induced ovulation or is other- 

 wise unique to the rabbit is not known ; com- 

 parable experimentation on the cat and fer- 



