36 FERTILIZATION 



the plasma membrane after attachment to the egg surface. Two 

 different compounds with these properties can be extracted from 

 spermatozoa, though there is no evidence that both can be ob- 

 tained from sperm of the same species. The existence of these two 

 classes of compounds, both of which are called sperm lysins in 

 the literature, makes the terminology confusing. One of them, 

 sometimes called Androgamone III (A.III), but more often sperm 

 lysin, was extracted with methanol from lyophilized sea-urchin 

 spermatozoa by Runnstrom et al. (1945). It diffuses through 

 cellophane and is therefore probably not a protein. It may be a 

 fatty acid. A similar substance, which is believed to be an 18- 

 carbon fatty acid with four double bonds, can be extracted from 

 mackerel testes. This lysin, which is found in the supernatant 

 fluid after spermatozoa have been centrifuged, is haemolytic and 

 activates unfertilized eggs, though it inhibits fertilization. Its 

 effects can be reproduced by detergents and bee venom. Osterhout 

 (1950, 1952) has obtained a similar substance by heating the sperma- 

 tozoa of Nereis succinea for ten minutes at 55° C. The compound 

 released into the sea water by this treatment is highly surface active 

 and activates eggs of the same species. Similar results are obtained 

 with the detergent Duponol, which is mainly composed of sodium 

 dodecyl sulphate. Some caution is necessary in the interpretation 

 of such experiments, as Osterhout (1953) has also shown that the 

 same treatment displaces protamine from Nereis spermatozoa, 

 though it appears from his brief note that the detergent-like com- 

 pound is responsible for the activation of eggs of the same species, 

 rather than protamine. 



The other compounds with lytic properties, which can be ex- 

 tracted from spermatozoa, are proteins. The most famous of 

 these is the enzyme hyaluronidase which causes dispersal of the 

 follicle cells that surround unfertilized mammalian eggs. Some- 

 thing similar to hyaluronidase is believed to exist in the spermatozoa 

 of Discoglossus pictus Otth (Hibbard, 1928; Parat, 1933), and of 

 marine invertebrates. Hartmann & Schartau (1939) were the first 

 to make this claim as regards sea-urchin spermatozoa and Monroy 

 & Ruffo (1947) said that they also could extract a substance from 

 these spermatozoa, by treatment with o-iN-acetic acid followed 

 by precipitation with acetone, which 'completely dissolved' (p. 

 604) the jelly round unfertilized eggs. There is some doubt about 

 these claims because sperm-antifertilizin sometimes has a curious 



