This document provides an overview of a presentation on the identification and comparison of pollen grains for forensic evaluation. It discusses pollen unit development and characteristics used for analysis like shape, size, symmetry, polarity, aperture, and microscopic examination. Pollen grains can be identified to genus or species level by comparing microscopic images to reference resources. Forensic officers utilize pollen analysis reports and comparison of pollen from crime scenes and suspects to aid criminal investigations and prosecution.

1. INTERNAL I EXAMINATION
PRESENTATION ON
IDENTIFICATION AND COMPARISION OF POLLEN GRAINS
FOR THE SUBJECT EVALUATION
CUTM 2902( UGFS S4-P2) FORENSIC BIOLOGY & WILDLIFE FORENSICS
PRESENTED ON : FEBRUARY 26, 2024
BY
BASANTA KUMAR PANIGRAHI
REGISTRATION NO. 222104320047
B.SC. FORENSIC CSIENCE (SEM.4) TO
TO
MS. TAMOSA MUKHERJEE
ASSISTANT PROFESSOR
SCHOOL OF FORENSIC
SCIENCES
BHUBANESWAR CAMPUS

2. Identification
and comparison
of pollengrains

3. Introduction. Sporoderm
Pollen unit. Sub-division of pollen surface
Shape. Microscopic analysis
Size. LO analysis
Apparatuses Pollen orientation
Symmetry. Role of Forensic Officer
Polarity Limitation
Contents

4. The pollen grains are
produced within the anther
of the flower. Pollen
mother cells originate
from the sporogenous
tissue of the anther which
later divide meiotically
to form four pollen grains
called tetrad.
Introduction
The pollen grains do not
remain united at maturity,
and are dissociated into
single pollen grain called
monad. Sometimes rarer
types like dyads (two
pollen grains), Octads
(eight pollen grains) and
Polyads (many pollen
grains) are also observed.

5. All pollen grains are in
tetrad stage during
development and the
polarity is determined in
this stage, prior to their
separation.
The imaginary line between
the proximal and distal
pole of the grain is
called the Polar Axis (PA)
which passes through the
centre of the spore to the
centre of the tetrad.
Pollen unit The plane perpendicular to
the polar axis through the
middle of the grain is the
equatorial plane
The pollen grains maybe
either apolar or polar.
Among the polar types the
pollen grains are either
isopolar or heteropolar
depending upon the
between two equal or
unequal polar faces.
.

6. Shape
The shape of the
pollen/spores may be
circular, elliptical, triangular,
rectangular, quadrangular or
in other geometrical shapes.

7. Pollen grains show a great
variety in their sizes. Smallest
pollen grains of about 5 x 2.4
µm is noted in Myosotis
palustris and some members of
Boraginaceae(forget-me-not),
while the largest pollen grains
(> 200 µm in diameter) are
observed in Curcurbitaceae,
Nyctaginaceae and Orectanthe
ptaritepuiane (Abolbodaceae).
Size

8. ✔ This system works very
well as long as the pollen
grains are embedded in
such a medium having
lower refractive index.
✔If a reverse sequence
occurred i.e. a pattern of
ornamentation that
appears to show “dark
islands” at high focus and
that become bright at low
focus, it is given the term
“OL- pattern”
✔ At lower focus holes
become lighter and
the sexine elements
become darken .

9. Aperature
Aperture is an opening or
thinning of the exine where
the in tine is usually thick.
With regard to their
position the apertures are
polar, global or equitorial.
Circumference of the grain
in polar view is called amb
(ambit, L. ambitus).

11. Symmetry
✔Pollen grains or spores are symmetric or asymmetric.
✔Radially symmetrical isopolar grains have one horizontal and
two or more vertical planes of symmetry. Radially symmetrical
heteropolar grains have no horizontal plane of symmetry.
✔Bilateral heteropolar pollen grains have two vertical planes of
symmetry. Bilateral isopolar grains have three planes of
symmetry, one horizontal and two vertical.

12. All pollen grains are in tetrad stage during
development and the polarity is
determined in this stage, prior to their
separation.
The imaginary line between the proximal
and distal pole of the grain is called the
Polar Axis (PA) which passes through the
centre of the spore to the centre of the
tetrad.
The plane perpendicular to the polar axis
through the middle of the grain is the
equatorial plane
.
The pollen grains maybe either
apolar or polar.
Among the polar types the pollen grains are
either isopolar or heteropolar depending upon
the between two equal or unequal polar faces.
Polarity

13. Sporoderm (pollen wall) Stratification
The mature pollen consists of two different layers, intine and
an outer acetolysis resistant layer exine composed of
sporopollenin.
The exine covers the entire pollen surface except germinal
apertures. The exine of pollen grains can be divided into an
outer sculptured sexine and an inner unsculptured nexine.
Sexine again consists of two layers: the outer, ectosexine and
inner, endosexine.
The nexine has been divided into two layers namely nexine I
and nexine II.
.

15. Sub- Divisions of the
pollen surface
✔ Apocolpium is a region at the pole
of a zonocolpate pollen grain
delimited by lines connecting the
apices of the colpi.
✔ Apocolpial field for a region at the
pole of a parasyncolpate pollen
grain, delimited by the margins of
anastomosing colpi.
✔ Mesocolpium is the area of a pollen
grain surface delimited by lines
between the apices of adjacent colpi.
✔ Mesoporium is the area of a pollen
grain surface delimited by lines
between the margins of adjacent
pores.

16. ✔In light microscopy (LM)
the morphological (pollen
shape) and surface
structures (exina) are
used for the
identification as well.
✔ Scanning electron
microscopy (SEM) which
allows a more accurate
determination of the type of
pollen grain based on
differences in surface
structures.
Microscopic Analysis
✔ Transmission electron
microscopy can provide
information on the
morphology of internal
structures.

17. Exine orientation
There are two different types of exine ornamentation, the
structure or texture and the sculpturing.
The structure comprises of all the internal (infratectal) baculae
of various form and arrangements.
All the ektexine characters belong to the structural features,
while the sculpturing comprises external (supratectal)
geometric features without reference to their internal
construction.

18. LO’ Analysis
✔ Erdtman (1952) proposed
the term LO-analysis
(derived from two Latin
words: lux means light and
obscuritas means darkness)
which is a method for
analysing patterns of sexine
organisation by means of
light microscopy.
✔ On focusing carefully down
through the exine their
appearance would change
due to a changing that
diffraction images
produced. For example,
when focused at high level.
✔ The surface types show the holes
or lower areas to be dark and any
raised areas or projecting
elements to be light

20. The highest correct classification
rate of 93.05% was achieved using
the phase contrast microscopy,
followed by the dark field
microscopy reaching 91.02%, and
finally by the light field
microscopy reaching 88.88%. The
most significant discriminant
characteristics were
morphological (2D and 3D) and
colour characteristics.

21. use these reports to aid in
their investigations, and
prosecutors frequently
present them as evidence in
court.
Consult a pollen
atlas or database
to help identify
the pollen grains
to the genus or
species level.
These resources
provide images and
descriptions of
pollen grains from
various plant
species.
Compare the
pollen grains
found at the
crime scene with
those from
potential
suspects'
clothing,
vehicles .
The Role of Forensic Officer

22. Limitation

23. Reference

24. Thank you