Through which cell of the embryo sac does the pollen tube enter the embryo sac?

What is the collective term for the events starting from the deposition of pollen grains on the stigma to the entry of the pollen tube into the ovule?

$A$: Initial growth of the pollen tube takes place at the expense of food present in the stigma and style.
$R$: The pollen tube travels intracellularly and chemotactically.

What is the function and location of the filiform apparatus in synergids?

After entering the embryo sac,the tip of the pollen tube swells and bursts due to:

What does the filiform apparatus do at the entrance into the ovule?