2. Contents
ď´ What are pollen grains?
ď´ Formation
ď´ Structure
ď´ Functions of pollen wall
ď´ Spectrum of possible pollen types
ď´ Pollination
ď´ Forensic palynology
ď´ What can Forensic Palynologists do?
ď´ How does Forensic Palynology work?
ď´ Case Study
ď´ References
3. What are Pollen Grains?
ď´ A pollen grain is a
microscopic body that
contains the male reproductive
cell (sperm cell) of a plant.
ď´ It is crucial in a plant's
fertilization process.
5. Formation
ď´ In angiosperms, produced by
the anthers of the stamens.
ď´ In gymnosperms, formed in
the microsporophylls of the
microstrobili (male pollen cones).
ď´ Microsporocyte is diploid and forms
four haploid cells, termed microspores,
via meiosis. This process is termed
microsporogenesis.
6. ⢠The four microspores form the double
wall of the pollen grain within a
structure made of callose.
⢠The callose is digested by callase and
the pollen grains are able to grow and
complete the formation of the endospore
and exospore.
7. Structure of Pollen grains
ď´ Intine, thin delicate wall of
unaltered cellulose.
ď´ Exine, tough resistant outer cuticularized
wall composed largely of sporopollenin.
Which in turn consists of 2 layers: tectum
and the foot layer, separated by a region
called the columella, which is composed of
strengthening rods.
ď´ The exine bears spines or warts, or is
variously sculptured, and the character of the
markings is often of value for identifying
genus, species, or even cultivar or individual.
(Exospore)
(Endospore)
(Nutritive Cell)
(Reproductive Cell)
8. ď´ The spines less than a micron in
length (spinulus, plural spinuli)
referred to as spinulose (scabrate),
or
ď´ The spines longer than a micron
(echina, echinae) referred to
as echinate.
9. Functions of Pollen Wall
ď´ Protects the sperm (while movement from anther to stigma).
ď´ Protects the vital genetic material from drying out and solar radiation.
ď´ The outer pollen wall, which prevents the pollen grain from shrinking and crushing
the genetic material during desiccation.
11. Pollination
ď´ The transfer of pollen grains to the female reproductive structure is
called pollination.
ď´ Pollination by wind: anemophilous.
ď´ Pollination by insects: Entomophilous.
12. Forensic palynology
⢠Pollen can tell a lot about where a person or
object has been region specific.
⢠Reveal the season in which a particular
object picked up the pollen.
