When a pollen grain lands close enough to the tip of an ovule, it is drawn in through the micropyle ( a pore in the integuments covering the tip of the ovule ) often by means of a drop of liquid known as a pollination drop.
42.
This migration of the border cells appears to be important for two reasons the formation of a structure called a micropyle, which is important for sperm entry, and for expressing the torso-like gene, which is an anterior-posterior patterning signal.
