palynology

1. Male Gametophyte -Morphology
Presented By-sapana prajapati
M.sc (sem-2)BotanyM.sc (sem-2)Botany
Roll No-202
CBO-404
Department of life sciences,
H.N.G.U.,PATAN

2. Content
• Introduction
• Pollen Wall features
• Scope of palynology
• Preparation of pollen grains

3. Introduction
• In the sexual process the pollen grain
produce male gametes,and egg secondary
nucleus are formed in the embryo sac.
• One male gamete fuses with the egg,and the
other with the secondary nucleus or the two
polars,resulting in triple fusion.

4. Cont…
• These processes are referred to as “double
fertilization,”a unique characteristic of the
angiosperms.
• The zygote usually develops into a bipolar
structure,the embryo,a product of tripal
fusion produces the endosperm.

5. Cont…
• Microsporogenesis:-Diploid cell=microspore
mother cell= = >Meiosis = = > 4 spores at the
end of process (i.e.,tetrad).Each microspore
becomes the pollen grain=malebecomes the pollen grain=male
gametophyte.

6. Cont…

7. Pollen wall features
• Pollen wall formation occurs in two phases.
• In the first phase,the wall material is
contributed to by the cytoplasm of the spore
alone which occurs during the tetrad stage.alone which occurs during the tetrad stage.
• In the secondary phase,which occurs the relese
of the microspores.

8. Cont
…
• The wall of a pollen grain is Made up of the
two layers the inner pectocellulosic
layer,which is degraded during acetolysis.
• The outer layer,exine,which is acetolysis and
biological degradation.
• The exine is composed of sporopollenin.

10. Scope of palynology
• Palynology is the science of pollen grains and
spores.
• The pollen grain:-Immature male• The pollen grain:-Immature male
gametophyte of seed plants.protected from
desiccation and mechanical damage by a wall
composed of two layers: intine and exine.

11. Cont…
• Exine:- outer most,resistant to
desiccation,decay and other mechanical
damage,with sporopollenin.
• Sporopollenin :- Polymer of carotenoids,fatty
acids,phenolics and phenylpropanoid.
• Intine :-inner layer,composed of the cellulose
and pectin.

12. Preparation of pollen grains
• Male gametophytes are contained within
pollen grains produced by the
microsporangia of anther.
• A pollen grain that has lanted on a stigma
germinates and the pollen tube of the male
gametophytes grows down to the ovary.

13. Cont…
• The ovule is entered by a pore called the
micropyle.
• Double fertilization occurs when the pollen• Double fertilization occurs when the pollen
tube discharges two sperm into the female
gametophyte with in an ovule.

14. Cont…
• One sperm fertilization the egg (now a zygote
2n) while the other combines with two nuclei
in the central cell of the female gametophyte
and intiates development of food-steringand intiates development of food-stering
endosperm (3n).

15. Cont…

16. Cont…
• Reference :-Taxonomy of angiosperm by
• B P Pandey
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