REPRODUCTIVE ENDOCRINOLOGY IN BIRDS 



1109 



C. FERTILIZATION AND SPERM PHYSIOLOGY 



1. In ]'ivo 



Unlike most mammalian sperm, avian 

 spermatoza retain their fertilizing capacity 

 for a long time in vivo. Exceptions are the 

 sperm of bats and of Armadillum vulgare 

 (Mann, 19541. The long functional survival 

 of the sperm is correlated with an interest- 

 ing anatomic adaptation of the infundibu- 

 lum of the oviduct. Van Drimmelen (1951) 

 found "sperm nests," small crypts, in the 

 oviduct with groups of sperm in them. The 

 heads of the sperm WTre oriented towards 

 the oviducal wall and the tails towards the 

 lumen (Fig. 18.9). Their location corre- 

 sponds to the site of fertilization experi- 

 mentally established by Olsen and Neher 

 (1948».\\ccording to Grigg (1957), who 

 passed a cellophane bag filled with Ringer's 

 solution through the oviduct and found 

 many sperm in the oviducal lumen, the 

 sperm are apparently released into the lu- 

 men of the oviduct by the passage of the 

 egg. 



The sperm nest may serve three purposes : 

 (1) to ensure the presence of large numbers 

 of sperm when required; (2) to supply nu- 

 trients to the sperm; (3) to remove the 

 waste products of sperm metabolism. Un- 

 fortunately, too little is known about avian 

 sperm metabolism to permit a reasonable 

 estimate of the importance of these nests. 



After their release into the oviducal lu- 

 men, the sperm can penetrate the vitelline 

 membrane and effect fertilization. Penetra- 

 tion of the vitelline membrane by more 

 than one sperm was noted in Aves by Olsen 

 (1942). These extra sperm are called the 

 supernumerary sperm, and special signifi- 

 cance has been given to them by Kushner 

 (1954). When the sperm, which fuses with 

 the female pronucleus, and the supernumer- 

 ary sperm are from different males, the re- 

 sulting chicks are alleged to have increased 

 vigor, to have increased hemoglobin con- 

 tent, and, in some cases, to have characters 

 from both sires (Kushner, 1954). The sug- 

 gestion of bipaternity in birds had been 

 made earlier by Hollander (1949) to ac- 

 count for some mosaics in which sex-linked 

 color patterns were involved in pigeons. The 



■T&'yT- 



Fifi. 18.9. Sperm nests in the infundibulum of 

 the oviduct of the fowl (van Drimmelen, 1951). 

 (From 0. C. van Drimmelen, J. Vet. Res., Siippl. 

 1,1951.) 



hyiwthesis of bipaternity was tested by Al- 

 terkirch, Hoffmann and Schaaf (1955) for 

 fowl. Male breeds with definite genetic 

 markers were used. In 57 offspring obtained 

 from hens mated in short succession to such 

 males, no evidence of bipaternity was found. 

 Nalbandov and Card (1943a) pointed out 

 that sperm, during their sojourn in the ovi- 

 duct, may undergo changes which cause ab- 

 normal development of the embryo. The ag- 

 ing of spermatozoa in the oviduct not only 

 decreased fertilizing capacity, but also in- 

 creased embryonic mortality. Dharmarajan 

 (1950) confirmed these results and estab- 

 lished that most of the abnormalities were 

 in the nervous and vascular system. Mc- 

 Cartney (1951) and Hale (1955) made sim- 

 ilar observations of increased embryonic 

 mortality in turkeys. Lorenz (1959) , who re- 

 viewed the literature w^hich appeared before 

 as well as after Nalbandov's and Card's 

 publication, concluded that the available 

 data were consistent with this concept of 

 increased embryonic mortality as a result 

 of fertilization by ''stale" sperm. The ob- 

 served deleterious effect of aging of gametes 

 has also been observed in mammals. In 

 them the aging of ova, but not of sperm, has 

 also led to abnormalities in embryos. This 

 interesting phenomenon is discussed in the 

 chaj^ter by Blandau and in a review by 

 Young (1953). 



It seems logical to assume that abnormal 

 embryonic development after fertilization 

 by stale sperm is the result of nuclear dam- 



