What is double fertilization? Describe fertilized embryo sac with a neat labelled diagram.

Explanation

i). Three cells are grouped together at the micropylar end and constitute the egg apparatus.
(ii). The egg apparatus consists of 2 synergids and one egg cell.
(iii). The synergids have special cellular thickening at the micropylar tip called filiform apparatus. It helps to guide the pollen tubes into the synergid.
(iv). Three cells are at the chalazal end are called the antipodals. The largee central cell has two polar nuclei. Thus, a typical mature angiosperm embryo sac is 8 - nucleate and 7 - celled.