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SPERM, OVA, AND PREGNANCY 



general being those of Anderson ( 1944) and 

 Emmens and Blackshaw (1956). Legal and 

 ethical aspects of artificial insemination in 

 man have been dwelt upon extensively in 

 the semiclinical literature (Haman, 1947; 

 Nicolle, 1949; Guttmacher, Haman and 

 MacLeod, 1950; Ellis, 1952; Pope Pius XII, 

 1957). 



According to various historic accounts, 

 the Arabians have for centuries practiced, if 

 not thoroughly understood, the art of arti- 

 ficial insemination in the breeding of their 

 horses.^ In more recent times Spallanzani 

 developed a method for the artificial in- 

 semination of amphibia and, in 1782, first 

 successfully inseminated a dog. Shortly 

 thereafter, the first successful insemination 

 of a woman was recorded (Home, 1799). 

 Now it is a common ])ractice, the world 

 over, for the selective breeding of various 

 species of mammals (Walton, 1958). The 

 techniques have also been applied, both for 

 academic and for practical aims, to other 

 types of animals, including fowl (Quinn and 

 Burrows, 1936; Van Drinnnolen, 1945), vi- 

 viparous fish (Clark, 1950), and insects 

 (Laidlaw and Eckert, 1950; Lee, 1950). 



Constant efforts are being made to im- 

 prove the dilution and storage media of 

 sperm for routine use in artificial insemina- 

 tion (see Salisbury, 1957). At present, 5- or 

 6-day survival of bull semen, diluted with 

 egg yolk-sodium citrate and stored in the 

 presence of antibiotics at 2 to 3°C., is about 

 all that can be expected. Most types of se- 

 men lose their fertilizing capacity much 

 sooner than this. It is a curious fact that 

 fowl sperm, which survive so well (2 or more 



^ Walter Heape ( 1898) recounted an interesting 

 tale which probably has some basis in fact : "It is 

 taken from a book written in the year 700 of the 

 Hejira, and therein is described how an Arab of 

 Darfour, the owner of a valuable mare on 'heat,' 

 armed with a handful of cotton wool which had 

 been saturated with the discharge from the vagina 

 of his mare, approached by stealth a valuable stal- 

 lion belonging to a member of a neighbouring hos- 

 tile tribe, a stallion whose services for his favourite 

 mare the owner was desperately anxious to obtain ; 

 and having sufficiently excited the animal with the 

 scent of the material he had brought, he obtained 

 spermatic fluid from him on the same handful of 

 cotton, and hastening back to his mare, which he 

 had been obliged to leave some distance away, 

 pushed the whole into her \agina, and obtained by 

 that means a foal." 



weeks) in the female genital tract, cannot 

 be iireserved in vitro more than a few hours 

 without decline in fertilizing capacity (Gar- 

 ren and Shaffner, 1952; Carter, McCartney, 

 Chamberlin and Wyne, 1957) . 



The most significant advance — certainly 

 the most striking — in the field of sperm 

 preservation during the past decade is the 

 remarkable success in maintaining cells in a 

 viable condition at extremely low tempera- 

 ture. The very early history began with 

 Mantegazza's (1866) and Davenport's 

 ( 1897) successful demonstrations that deep- 

 frozen ( — 17°C.) human sperm could regain 

 motility. Despite other attempts to improve 

 the degree of recovery by the addition of 

 various substrates and by control of tem- 

 perature changes, a marked measure of suc- 

 cess was to await the discovery of Polge, 

 Smith and Parkes (1949), who showed that 

 eciuilibration of the semen with glycerol be- 

 fore freezing greatly enhances sperm recov- 

 ery and motility after warming to room 

 temperature. This work, on rooster and hu- 

 man spermatozoa, catalyzed many investi- 

 gations of the problem M'ith the result that 

 today there are few common mammals 

 whose sperm have not been vitrified, stored 

 at —79° or — 196°C., and warmed up for 

 observation of motility or used in breeding 

 experiments (Emmens and Blackshaw, 

 1956; Polge, 1957; VanDemark, Miller, 

 Kinney, Rodriguez and Friedman, 1957; 

 Martin and Emmens, 1958). The presence 

 of glycerol is essential, in concentrations be- 

 tween 10 and 15 per cent, for bull sperm, to 

 20 per cent for those of fowl (Martin and 

 Emmens, 1958). Bull spermatozoa have 

 been stored successfully in this fashion for 

 periods up to 6 years (Walton, 1958). 



Artificial insemination with previously 

 deep-frozen, thawed sperm has resulted in 

 conception and viable young in a number of 

 animals. The degree of fertility varies, be- 

 ing low in the rabbit and as high as in nor- 

 mal matings in the bull (Emmens and 

 Blackshaw, 1956). Pregnancies have been 

 reported for several women inseminated 

 with spermatozoa treated in this manner 

 (Bunge and Sherman, 1954). 



The advantages of the perfection of the 

 low-tempcrature method for the preserva- 

 tion of animal sperm are obvious. In the case 

 of bull semen, for example, the procedure 



