The fine structure of the micropyle and the initial stages of sperm entry into the egg of the artificial multiple triploid carp were observed by means of scanning electron microscopy. Only one micropyle at the animal pole of the mature egg could be found. The aperture of the outer opening of the micropylar canal was only wide enough to admit one spermatozoon to pass through. A series of ordered sequence of motile events after fertilization were observed, which including that the sperm attached to the surface of the mature eggs and passed through micropylar canal, cottonlike substances closed up the micropylar canal, cortical vesicles underwent exocytosis and digesting, the vitelline envelope was transformed into fertilization envelope and so on. In addition, a preliminary discussion on the mechanism of polyspermic fertilization in the artificial multiple triploid carp was described in this paper.
