In generally , to make sure of sperm enter into lii ing egg zs considerable coif-ficult. V he got eeellent obserations by use of the elot.roni scanning microsenpe.he results pan be summarised as follows: 1.intured egg he bream 3legaLobru·mrc G-minrrbds Riehardsun is snrru-ended hr the thick chorion. There is : Panel-Iike depression on the chorion nearbythe nnim,l pole. L miorupyle is at tha haftzn of tho depression. L nicrupylar tubr,5 dia.n ieier, c;onnels the ruicrupyle into the protoplasmic gerruirzal disL. I heaerosomles sperm cont:zct vth tbc egg rytaplasm through this nlicropylar tube. Inzddition, tliere are numerous infinitesimal pares arc found all over the surface ofrh.)rion. 2 .he spna oI the breanz enter into tho egg instantly, and all mioropylar t.nhesare sealed by the fertilised ping ithin 30 seconds after insemizicztion, the sherzn entrzsthc cgl; and cxst the flagellum. 3. tllthough only one sperm is alloned to enter into tho egg not·lolly，but agreat quntity of super auizzerary sperms is eoessfrry to raise the rate of ert ilition.Hone-er, more than one sperm enters into the egg, the number of chronosrunill he riscd than the normal axxd cause abortion early enahrogeneaia, thus aferfed plug is Formed at the inner openhg of the micropylar tube.