EXPERIMENT 2(A)
Aim parenchyma. collenchyma and sclerenchyma tissues in plants, from prepared slides and to
To identify
draw their labelled diagrams.
Materials Required
Prepared slides of different types of plant tissues.
Procedure
Place the permanent slides of various plant tissues (parenchyma, collenchyma and sclerenchyma)
one by one under a compound microscope.
" Observe these slides first under low power and then under high power.
" Note down the characteristic features of various plant tissues from the slides.
" Identify the tissues with the help of charts.
" Draw diagrams of the tissues as seen under the microscope.
Observations
" Observe and record the features of various plant tissues.
Parenchyma
ldentifying Features
" Parenchymatous cells are isodiametric (almost equal in length and width).
" Intercellular spaces are generally present for exchange of gases.
" Each cell possesses a large central vacuole and a peripheral cytoplasm with a prominent nucleus.
" These cells are present in the soft areas of the stems, leaves, root, flowers, fruits etc.
" The important functions of these cells are storage, photosynthesis (chlorenchyma), helping in
floating (aerenchyma) etc.
Collenchyma
ldentifying Features
" Collenchymatous cells are either isodiametrie or
somewhat elongated.
" Intercellular spaces are generally absent.
" Each cell possesses a large central vacuole and a peripheral cytoplasm with
" Thickenings are present at corners. prominent nucleus.
. The cells are present below the
epidermis in petiole, leaves and stems of herbaceous dicots.
.Important functions of these cells are to provide mechanical
storage, photosynthesis etc. strength, prevent tearing of leaves,
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LABORATORY MANUAL SCIENCE-IX
Thin cell wall
Vacuole
Intercellular
spaces
Nucleus
A B
Transverse section (TS) Longitudinal section (LS)
Parenchyma
Thickening
at the Corners
Vacuole
Nucleus
A
Transverse section (TS) Longitudinal section (LS)
Collenchyma
LABORAIORY MANAL SCIENCEI 145
Sclerenchyma
ldentifying Features little or no protoplasm.
Sclerenchymatous cells are thick-walled hard cells with
These cells are generally divided into two types:
(0 Fibres sclerenchyma (i0) Sclereids
spindle-shaped with pointed end walls.
Pibres are highly elongated (1-90cm). narrow and
Adjacent fibres possess simple oblique pits.
They do not perform any function at maturity because they are empty and dead (except mechanical
strength).
Selereids are highly thickened, dead sclerenchymatous cells with very narrow cavities.
" They may occur singly or in groups.
They provide stiffness to the parts in which they Occur.
Table 1: General features of Parenchyma, Collenchyma and Sclerenchyma
Features Parenchyma Collenchyma
Cell wall
Sclerenchyma
Thin Unevenly thick Thick
Pits (unthickened area
in cell wall) Absent Present Present
Arrangement Generally loose Compact and close Compact and close
Shape of cell
Round, oval or polygonal Elongated in vertical
Isodiametric or elongated section and polygonal in
cross section
Intercellular spaces Present
Generally absent
Lumen Absent
Present (Large) Present
Cytoplasnm Present Highly reduced
Present
Nucleus Absent
Present
Present
Living/Dead Living
Absent
Living Dead
Lumen
Cell wall
-Pit
Transverse section (TS) Longitudinal section (LS)
Lumen
Pit canal
Thickened
cell wall
Sclereids (Stone cells)
Sclerenchyma
EXPERIMENT 2(B)
Aim and nerve cells in animals, from prepared slides
smooth and cardiac muscle fibres
To identify striped.
and to draw their labelled diagrams.
Materials Required
types of animal tissues.
" Prepared slides of different
Procedure smooth and cardiac one by one, under
muscle fibres-striped,
Place the permanent slides of various
a compound microscope.
and then under high power.
" Observe them first under low power
light and dark bands.
Try to see an alternate arrangement of
" Also observe some nuclei along the fibre.
" Identify the tissues with the help of charts.
microScope.
Draw diagrams of the tissues as seen under the fibre.
Replace the permanent slides of muscle fibres by the permanent slide of a nerve
"
help of charts.
" ldentify different parts ofa nerve cell with the
e Draw diagram of the nerve cell as seen under the
microscope.
Observations
present in animals.
" Observe and record the features of striped muscle fibres and nerve cells
MUSCuLAR TISSUE
Striated Muscles (Striped muscles)
ldentifying Features
" These muscles work according to our will (voluntary) and get tired when overworked.
" Striated muscle cells are long cylindrical fibre that are enclosed in a membrane called sarcolemma.
" The cytoplasm of each fibre is called as sarcoplasm. It is divided into large number of myofibrils.
" Each myofibril bears alternate light (-band) and dark bands (A-band) giving the characteristic
striated appearance.
. The muscle fibres are multinucleated. The nuclei lie towards the
periphery of the fibres.
. These muscles are present in the general musculature of our body.
Non-Striated Muscles
ldentifying Features
. These fibres do not work according to our will (involuntary) but work continuosly without getuis
tired.
Unstriated muscle cells are spindle-shaped and are not
enclosed by sarcolemma.
LABORNTORY MANUAL SCIENCEN
Muscle fibres
Myofibrils
Nucleus
Sarcoplasm
Non-striated muscles
Dark bands
Peripheral nucleus
Light bands
Striated muscles
The
The cytoplasnm (sarcoplasm) surmounding the nucleus is clear while the remaining sarcoplasm has
myofibils The myofibrils do not show light and dark bands (smooth appearance).
There is asingle centrally located nucleus (uninucleate) in the cytoplasm.
There are found in the alimentary canal, blood vessels.
Cardiac Muscles
ldentifying Features
These fibres do not work according to our will (involuntary) and work continuously
without getting tired. throughout life
They show alternate dark and light bands.
These fibres are branched and uninucleate.
These fibres are characterised by the presence of intercalated discs.
These fibres are present only in the heart region of the body.
Table 2: Differences among Non-striated, Striated and Cardiac Muscles
Features Non-striated muscles Striated muscles Cardiac muscles
Involuntary/voluntary Involuntary Voluntary Involuntary
Shape and size Long and spindle Long and cylindrical Short and cylindrical
Fibres are not Interconnected by
Interconnections in fibres Not interconnected
interconnected oblique bridges
Dark and light bands in Absent Present Present
myofibrils
Fatigueness Not fatigable Fatigable Immune to fatigue
0 NERVOus TISsUES
ldentifying Features
Anerve cell or aneuron has a large body called cyton with a prominent nucleus.
- Acyton has cytoplasmic projections called dendrons, which are further divided into dendrites. One
of the projections is long and is known as axon. A group of axons held together by a connective
tissue constitute a nerve.
The cytoplasm of a neuron is called neuroplasm which contains nissl granules.
Amyelin sheath is present over the axons--myelinated nerve fibre. Amembrane called neurilemma
surrounds the myelin sheath. At the node of Ranvier, myelin sheath is absent.
Intercalated disc
Striations
Oblique bridge
Nucleus
Cardiac muscles
Dendrites
Dendron
Cyton Nucleus
Nissl granule
Myelin
sheath
Nucleus of
schwann cell
Node of
Ranvier
Axon
Nerve ending
Neuron
LABORATORY MANUAL SCTENCE-DX 151
