This document discusses fertilization in plants. It begins by defining fertilization as the fusion of male and female gametes to form a zygote. It states that the pollen grain produces male gametes and the embryo sac produces an egg cell and polar nuclei. There are three types of pollen tube entry: porogamy through the micropyle, mesogamy through the integuments, and chalazogamy through the chalaza. The document then describes double fertilization, where one male gamete fuses with the egg nucleus to form a zygote, and the other fuses with the two polar nuclei to form the endosperm nucleus.

1. Fertilisation
Dasari. Sreekanth. M.Sc, NET, TS/AP-SET, (Ph.D).
Department of Botany,
Osmania University,
Hyderabad.
Email id: shreekanthdasari@gmail.com

2. Fertilisation
 Fertilisation is the fusion of the male (n)
and female (n) gametes to produce a
zygote (2n)
 The pollen grain produces the male
gametes
 Embryo sac produces an egg cell and polar
nuclei

3. Fertilisation
 Entry of pollen tube is 3 types
 A. Porogamy
 B. Mesogamy
 C. Chalazogamy

4. Fertilisation
 Porogamy: enters through micropyl

5. Fertilisation
 Mesogamy: enters through integuments.

6. Fertilisation
 Chalazogamy: enters through Chalaza.

7. Pollen Grain

8. Pollen Tube

9. Tube Nucleus
Generative Nucleus

11. Tube nucleus disintegrates
Mitotic division of generative
nucleus to form 2 male gametes

13. 1 Male gamete fuses with the 2 polar nuclei to
form the triploid endosperm nucleus
1 male gamete fuses with the egg nucleus
to form the diploid zygote

14. 3N endosperm nucleus
2N Zygote
Double fertilisation

15. 15
DOUBLE FERTILISATION (Syngamy and triple fusion)
Pollen tube into
synergid
• the pollen tube releases the two male gametes into the cytoplasm of the
synergid.
Syngamy
• the pollen tube releases the two male gametes into the cytoplasm of the
synergid. One male game fuse with egg cell and produces zygote.
• Diploid Zygote formation - zygote develops into an embryo.
Triple fusion
3 haploid
nucleus fuse
• other male gamete moves towards the two polar nuclei located in the central
cell and fuses with them to produce a triploid PEN This central cell forms
• primary endosperm cell (PEC) and develops into the endosperm

16. The end-
POST-FERTILISATION : STRUCTURES AND
EVENTS