Dynamical Action of Sperm Penetration Into The Egg of Misgurnus anguillicaudatus

The surrounding membranes (chorion) of the eggs in two Chinese fishes (Misgurnus anguillicaudatus,Megalobrama amblycephala) are all solid.The sperm penetrating into the mature egg is restricted in the micropylar canal of the chorion.There is a funnel-like depression at the opening of the micropylar canal and an outer opening of the canal is situated at the bottom of the depression,therefore this depression is the vestibule of the micropyle apparatus.There are whirlpool-like structures on the bottom surface of the depression and the inner wall of the micropylar canal.According to computation,there exist in the upper whirlpool of the micropyle powerful centripetal forces,which collect sperms and draw the sperms into the micropylar canal.Before fertilization of these studied fsihes,there is physical movement which forces sperms into the mature eggs,besides the chemical substances secreted by the mature eggs and sperms.On the basis of the law of individual variability,it is inferred that some kinds of fishes in the southern hemisphere perhapes have right whirlpool-like struture of the micropyle,because there are left whirlpool-like structures of the micropyle studied fishes in the northern hemisphere.