1. Pollen tube carries two male gametes and the vegetative nucleus.
2. Pollen tube grows through the tissues of stigma and style to reach the ovary.
3. It enters the ovule through the micropyle and then enters the embryo sac through the filiform apparatus of one of the synergids.

1. It is a case of polyembryony, the phenomenon of occurrence of more than one embryo in a seed.
2. It is possible in the following ways:
(i) Some of the nucellar cells surrounding the embryo sac start dividing, protrude into the embryos.
(ii) Synergids of the embryo sac divide and form embryos.

A typical microsporangium is surrounded by four wall layers, i.e. the epidermis, endothecium, middle layers and the tapetum. The outer three wall layers are protective in function and help in dehiscence of anther to release pollen grains.
The innermost layer (tapetum) nourishes the developing microspores or pollen grains. The cells of tapetum possess dense cytoplasm and generally have more than one nucleus.

When the anther is young, a group of compactly arranged homogenous cells called the sporogenous tissue occupies the centre of each microsporangium.

(i) The process of formation of megaspores from Megaspore Mother Cell or MMC (diploid) is called megasporogenesis.
It occurs inside the nucellus of developing ovule of angiosperms. The process begins very early when nucellus is not conmpletely surrounded by the integuments. The MMC (a large cell containing dense cytoplasm and a prominent nucleus) enlarges in size and divides by meiosis. It first divides transversely into two cells called megaspore dyad. 
These two cells apgain divide transversely as a result, a linear row of four haploid cells megaspore tetrad is produced.

Out of the four megaspores one situated at the chalazal end remains functional and the rest three gradually degenerate. Such a development of embryo sac is called monosporic development, e.g. Pobygonum.
(ii)

- After entering one of the synergids,the pollen tube discharges the two male gametes into the cytoplasm of that synergid.
- One of the male gametes moves towards the female gamete/egg and fuses with it; this fusion is called syngamy and it results in the formation of a zygote.
- The second male gamete moves towards the two polar nuclei in the central cell.
- The two polar nuclei just fuse to form a secondary nucleus and the second male gamete fuses with the secondary nucleus in the central cell; this fusion is called triple fusion and, it results in the formation of a triploid primary endosperm nucleus.
- Since two fusions, syngamy and triple fusion occur in an ovule, the phenomenon is known as double fertilisation in angiosperms. 
Post-fertilisation events:
- The central cell becomes the primary endosperm cell after triple fusion; the primary endosperm nucleus develops into the endosperm.
- Zygote develops into the embryo.
- Antipodals and synergids degenerate.
- The integuments develop into the seed coat.
- The ovule becomes transformed into a seed.