Question

what facilitates entry of male gamete into the ovule

Answer 1

The sperm head, when it is in the contact of the female ovule develops a weak polarisation wave and Ca2+ wave by which plasma membranes of the two dissolve immediately after the contact is established and the tail of the sperm is left outside (one more key role is played by the enzyme which is placed or coated on the top of the sperm head known as hyalouranidase) subsequently a previtelline layer is created to prevent or facilitate the entry of the second sperm.