126 MAMMALIAN FERTILIZATION 



in immunological tenns, it is a different subject matter. It has 

 been claimed that agglutinated sperm are unable to fertilize 

 (Anderson, 1945; Lindahl and Kihlstrom, 1954), but contradic- 

 tory evidences are available. For instance, intensively aggluti- 

 nated sperm were recovered from the rabbit vagina, but young 

 rabbits were obtained (Kato, 1938). Agglutinated rabbit sperm 

 is invariably recovered from the uterus, and yet fertilization oc- 

 curs after the deposition of uterine sperm into the Fallopian tube 

 (Chang, 1955a). 



Lindahl and Kihlstrom ( 1952 ) reported that mammalian sper- 

 matozoa agglutinate when semen is stored for some time un- 

 diluted or diluted with saline. They interpreted this to be due to 

 a spontaneous inactivation of "sperm antagglutin" produced in 

 the prostate gland. Lindahl and Nilsson (1954) further reported 

 the finding of a "female sperm antagglutin" present in the fol- 

 licular fluid and in the Fallopian tube of estrous rabbit. Since the 

 mammalian egg is suspended in the follicular fluid, if there is a 

 "fertilizin" diffused from eggs to activate and to agglutinate 

 sperm, as in the case of the sea urchin, follicular fluid should in- 

 duce the activity of sperm as reported by Kurzrok et al. ( 1953 ) 

 rather than induce the disappearance of agglutination as reported 

 by Lindahl and Nilsson ( 1954 ) . This important finding of "ant- 

 agglutin" in the male and female tract of mammals may have 

 other implications for mammalian fertilization which need fur- 

 ther elucidation. 



Conclusions 



The understanding of physiological changes at sperm penetra- 

 tion, activation, and syngamy is very limited. This is mainly due 

 to the fact that there is no simple and repeatable procedure to 

 fertilize mammalian eggs in vitro. The reaction substances present 

 in sperm and eggs at fertilization as elucidated in the fertilization 

 of marine species may not be transferred to mammalian fertiliza- 

 tion at present. 



The Fallopian tube may play a very important role in mam- 

 malian fertilization, especially at the time of sperm penetration 

 through the intercellular spaces of the corona radiata and the 



