Practical Demonstration of Slide Preparation of Dividing Cells

Purpose of the Practical Demonstration

To understand and observe the various stages of cell division occurring within a sample.
To practice and develop the skills necessary for accurate and safe slide preparation and microscope techniques.

Materials Required

Sample (e.g., onion root tip).
Microscope slide and coverslip.
Condensed acetic acid or ethanol for fixation.
Hydrochloric acid (HCl) for maceration.
Orcein stain that enables visualisation of chromosomes.
Microscope for observation.

Preparation Process

The sample is first fixed in condensed acetic acid or ethanol. This process preserves the sample by halting cellular activity and hardening the structure.
The fixed sample is then immersed in hydrochloric acid to macerate it. This softens the tissue, aiding in separating the individual cells.
The macerated sample is placed on a slide and gently squashed to form a thin layer.
Staining is carried out by applying orcein stain which helps to visualise chromosomes under a microscope.
The stained sample is then covered with a coverslip carefully to prevent air bubbles or damage to the sample.

Microscopic Examination

The prepared slide is observed under the microscope.
It begins with a low power lens, and gradually the magnification is increased for detailed observation.
Identifying cell division stages – identify the characteristic shapes of cells in the following stages: prophase, metaphase, anaphase, telophase and cytokinesis.

Safety Precautions

Since the process involves the use of chemicals like ethanol and hydrochloric acid, safety goggles and lab coats should be worn to prevent any accidental splashes.
The use of a dissection microscope is recommended while handling delicate parts of the sample.
Dispose of all chemical solutions and biological samples safely following laboratory guidelines.

By undertaking this practical, you’ll not only learn about the theory of cell division but also understand the importance of proper slide preparation and microscope techniques in observing this fundamental biological process.