19. How does the male
gamete penetrate the egg
cell? How does the female
gamete protect itself from the
entrance of more gametes
after the entrance of the first
sperm cell?

Gap-fill exercise

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The sperm cell that the egg cell
triggers acrosome reaction, a
process which hydrolytic enzymes of
acrosome are released on
external surface of the pellucida
(the protective layer surrounds the
eggcell). A of this layer is
by the acrosomal enzymes
the sperm cell to the
plasma membrane of eggcell
carrying out fecundation.

the moment that the cell
makes contact with eggcell
membrane a chemical of this
membrane occurs. secreted by
exocytosis (cortical ) make the
zona pellucida to bind to other
cells (zonal reaction) and
male gametes cannot enter egg cell.