What is CSEEL and what does it offer?

CSEEL (Center for Scientific Exploration and Experiential Learning) is a premier Indian STEM educational initiative offering hands-on science experiments, 3D live laboratory simulations, curriculum-aligned project kits, teacher training workshops, and national science conclaves aligned with NEP 2020.

How does CSEEL support NEP 2020 experiential learning?

CSEEL shifts education from rote memorization to active inquiry and hands-on experimentation. Students observe, build, analyze, and apply scientific concepts to real-world challenges, developing critical thinking and scientific temper as envisioned by NEP 2020.

What subjects and classes are covered in CSEEL simulations and experiments?

CSEEL provides comprehensive physics, chemistry, biology, environmental science, and applied robotics experiments and virtual simulations for students from Class 6 through Class 12, mapped to CBSE, ICSE, and state curricula.

How can schools, educators, and students access CSEEL programs?

Institutions, teachers, and students can explore live simulations, order DIY lab kits, register for national seminars, and join the CSEEL EduNetwork by visiting https://www.cseel.org.

Temporary Mount of Onion Peel Epidermal Cells

Experiment video

What you will learn

Prepare a temporary stained mount of onion bulb epidermal peel and observe the structural organization of plant cells (cell wall, nucleus, cytoplasm, and vacuole) under a compound microscope.

Materials needed

Fresh Onion Bulb
Fresh Onion Bulb
₹50
What is it?
Compound binocular biological laboratory microscope with LED sub-stage illumination.
Specifications
Magnification
40×, 100×, 400×, 1000×
Objectives
Achromatic 4×, 10×, 40× spring, 100× oil
Eyepieces
WF10× / 18 mm field of view
Condenser
Abbe 1.25 NA with iris diaphragm
Methylene Blue / Safranin Stain Solution (0.5%) dropper bottle
Methylene Blue / Safranin Stain Solution (0.5%) dropper bottle
₹95
What is it?
Safranin O biological histological nuclear stain (0.5% aqueous solution).
Specifications
Dye Content
≥ 85% certified biological stain
Solvent
50% ethanol / 50% distilled water
Target
Binds nucleic acids (red) and lignified cell walls
Bottle
100 mL dropper bottle
Glycerine (pure laboratory grade) dropper bottle
Glycerine (pure laboratory grade) dropper bottle
₹140
What is it?
Pure analytical grade Glycerine (Glycerol) mounting medium and cover slips.
Specifications
Refractive Index
nD = 1.474 (ideal match for glass)
Purity
≥ 99.5% AR grade
Coverslips
No. 1 thickness (0.13 – 0.17 mm), 22 mm × 22 mm
Compound Light Microscope (10x, 40x objectives)
Compound Light Microscope (10x, 40x objectives)
₹185
What is it?
Standard laboratory apparatus used in Temporary Mount of Onion Peel Epidermal Cells.
Specifications
Category
Biology Apparatus
Grade
CBSE / NEP 2020 Laboratory Standard
Glass Microscope Slides & Cover Slips (No. 1 thickness) box
Glass Microscope Slides & Cover Slips (No. 1 thickness) box
₹230
What is it?
Standard laboratory apparatus used in Temporary Mount of Onion Peel Epidermal Cells.
Specifications
Category
Biology Apparatus
Grade
CBSE / NEP 2020 Laboratory Standard
Watch Glass, Forceps, Dissecting Needle, and Camel Hair Brush set
Watch Glass, Forceps, Dissecting Needle, and Camel Hair Brush set
₹275
What is it?
Standard laboratory apparatus used in Temporary Mount of Onion Peel Epidermal Cells.
Specifications
Category
Biology Apparatus
Grade
CBSE / NEP 2020 Laboratory Standard
Filter Paper / Blotting Paper strips pack
Filter Paper / Blotting Paper strips pack
₹320
What is it?
Standard laboratory apparatus used in Temporary Mount of Onion Peel Epidermal Cells.
Specifications
Category
Biology Apparatus
Grade
CBSE / NEP 2020 Laboratory Standard

Tick items as you collect them. Tap + to see the product, specifications and buy options.

Stay safe

Always use a camel hair brush to transfer delicate peels; forceps can tear or crush cell walls.
Do not let the peel dry out at any stage of preparation.
Lower the coverslip slowly to avoid trapping air bubbles (air bubbles appear as thick black-rimmed rings).
Wipe off excess glycerine with blotting paper so microscope stage remains clean.

Steps

0 of 7 steps done

1Cut a fresh onion bulb and peel off a fleshy scale leaf.
Observation
Peel a thin, transparent epidermal layer from the concave inner surface of an onion fleshy scale leaf.
Safety
Use fine forceps gently to avoid tearing or wrinkling the delicate epidermal membrane.
2Bend the leaf inward until it snaps, then use fine forceps to gently peel off the thin, transparent inner epidermal membrane.
Observation
Place peel immediately in a watch glass containing water to prevent desiccation and cell shrinkage.
Safety
Keep specimen submerged; dehydrated cells collapse and distort.
3Immediately transfer the epidermal peel into a watch glass containing water using a camel hair brush to prevent folding or drying.
Observation
Transfer to watch glass containing dilute Safranin stain for 2 to 3 minutes; rinse excess stain in fresh water.
Safety
Safranin stains skin and clothing intensely; use forceps and wash brushes.
4Add 2-3 drops of Safranin stain to the watch glass and let the peel stain for 2 minutes.
Observation
Mount peel in center of clean glass slide in a drop of pure glycerine; lower coverslip at 45° using needle.
Safety
Lower coverslip slowly with mounting needle to prevent trapping air bubbles.
5Transfer peel to another watch glass of clean water to rinse off excess stain.
Observation
Blot excess glycerine with filter paper; examine under 10× low power, then switch to 40× high power.
Safety
When focusing 40× high power, only use fine adjustment knob to prevent crashing objective into glass slide.
6Place the stained peel flat in the center of a clean glass slide and add a single drop of glycerine.
Observation
Observe crisp rectangular brick-like cells with distinct dark red stained nuclei and cell walls.
Safety
Clean microscope stage and oil immersion lenses with lens tissue after viewing.
7Lower a clean coverslip gently at a 45° angle using a needle to prevent air bubble formation. Blot excess fluid and examine under 10x, then 40x.

Tap + on a step to see what you will observe and any safety tips.

Record your observations

Magnification Objective	Observed Cell Feature	Visibility & Description	Organelles Visible
Low Power (10×)	Cell arrangement & shape	Rectangular, brick-like cells packed tightly in sheets	Cell walls, prominent boundaries
High Power (40×)	Cell Wall & Cytoplasm	Distinct double-line cellulose cell wall, granular cytoplasm	Cell wall, thin peripheral cytoplasm
High Power (40×)	Nucleus	Dense, spherical, darkly stained body pushed to one side	Nucleus, prominent nucleolus visible
High Power (40×)	Central Vacuole	Large transparent central vacuole occupying >80% volume	Large central sap vacuole, tonoplast boundary

Tap a highlighted cell to write your own observation.

Result and conclusion

Clear rectangular epidermal plant cells observed with distinct cell walls, prominent darkly-stained peripheral nuclei, and large central vacuoles.

Cell Dimension = Field of View Diameter / Cell Count = 1500 μm / 6 = 250 μm length

Observation	What it means
Typical Plant Cell Architecture	Cells display classic rigid cellulose cell wall, large central sap vacuole, and peripheral cytoplasm.
Nucleus Eccentric Position	The huge central vacuole pushes the nucleus and cytoplasm against the peripheral cell boundary.
Absence of Chloroplasts	Because onion bulbs grow underground as storage organs, epidermal cells contain zero chloroplasts (non-photosynthetic).
Staining Specificity	Safranin or acetocarmine binds preferentially to nucleic acids and cell wall polysaccharides, giving high optical contrast.

Cell Length vs Cell Width Distribution in Onion Epidermis

Sample readings. Replace with your own results.

Experiment photos

Before the experimentDuring the experimentResult