Angiosperms have well covered seed it has two types monocotyledons and dicotyledons it consist of 3 celled egg apparatus?:2 synergies, 3 antipodals, 3egg cells and 2 polar nuclei later they fuses and forms diploid nucleus called later pollination and then one male gamete fuses with female ones and next gamete fuses with diploid nucleus and forms diploid primary endosperm nucleus thus double fertilisation.

Mature Angiosperm Embryo Sac
The mature angiosperm embryo sac is a crucial structure within the female gametophyte of flowering plants. It is formed through the process of megasporogenesis and megagametogenesis. The mature embryo sac is located within the ovule of the flower and plays a key role in the process of sexual reproduction in plants.

Structure of Mature Angiosperm Embryo Sac
- The mature angiosperm embryo sac is a seven-celled structure with eight nuclei, arranged in a specific pattern.
- It consists of three antipodal cells, two synergids, one egg cell, and one central cell with two polar nuclei.
- The egg cell is located at one end of the embryo sac and is responsible for fertilization by the pollen grain.
- The central cell contains two polar nuclei, which will eventually fuse with the sperm cell to form the endosperm, a nutrient-rich tissue that nourishes the developing embryo.

Function of Mature Angiosperm Embryo Sac
- The mature embryo sac plays a crucial role in the process of double fertilization, where one sperm cell fertilizes the egg cell to form the zygote, while the other sperm cell fuses with the polar nuclei to form the endosperm.
- It provides a protective environment for the egg cell and facilitates the process of fertilization.
- The development of the embryo sac is essential for the successful reproduction and propagation of flowering plants.
In conclusion, the mature angiosperm embryo sac is a specialized structure within the female gametophyte of flowering plants, essential for the process of sexual reproduction. Its unique structure and function play a vital role in the successful development of the embryo and subsequent formation of seeds in angiosperms.