To prepare stained temporary mounts of human cheek cell and to record observations and draw labelled diagrams - Class 9th Science Lab Work
Experiment - 4
Aim
To prepare a temporary mount of human cheek epithelial cells, and to study its characteristics.Theory
The body of all animals including humans is composed of cells. Unlike plant cells, animal cells do not have cell wall. The outermost covering of an animal cell is a cell membrane. The cytoplasm, nucleus and other cell organelles are enclosed in it. Epithelial tissue is the outermost covering of most organs and cavities of an animal body.
Materials Required
Methylene blue stain, glycerine, a compound microscope, slide, cover slip, a clean spatula or a toothpick, a brush, a needle, and a piece of blotting paper.
Procedure
Step 1: We rinsed our mouth with water.
Step 2: With the help of a clean spatula or a toothpick, the inner side of the cheek is gently scrapped.
Step 3: The scrapped material is transferred into a drop of water and taken on a clean slide.
Step 4: With the help of a needle the material is uniformly spread.
Step 5: A drop of methylene blue stain is added. After 3 minutes a drop of glycerine is added over it.
Step 6: A clean cover slip is placed over the glycerine. Excess glycerine is removed from the edges of cover slip with the help of a piece of blotting paper.
Step 7: The slide is observed under microscope, first under low power and then under high power.
Observation Table
| Sl. No. | Feature | Observation |
| 1 | Shape of cells | polygonal |
| 2 | Arrangement of cells | compact |
| 3 | Inter -cellular spaces | present |
| 4 | Cell membrane | present |
| 5 | Cell wall | absent |
| 6 | Cell contents | nucleus, mitochondria |
| 7 | Vacuoles | absent |
Results and Discussion
Epithelial cells are small, polygonal in shape and compactly arranged to form a continuous layer. The cells are without cell wall. Cell membrane encloses a distinct nucleus and a vacuole. Epithelial tissue forms the outermost covering of almost all the organs and various cavities of animals and human.
Precautions
1. Cheeks should be scrapped gently to prevent injury.
2. Spread the material on the slide so that it forms a thin uniform layer.
3. Avoid over staining (or under staining) of the material.
4. While mounting the cover slip, avoid entry of air bubbles.
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