Mitosis and meiosis are the stages of cell division. In a eukaryotic cell. A single cell divides, this division takes a series of fundamental cells . which includes Interphase ( S1, G1,G2 etc ) , Prophase, Metaphase, Anaphase, Telophase . In Meiosis there are some more complex events occur which include prophase 1, where crossing over and tetrad form in a nutshell in meiosis diploid cell becomes haploid and it occurs only in germ cells . but today our focus is beyond from theory we will look at the practical way how to observe these elegant stages in a cell
Lets begin with first step that is the technique which implies the study and observation possible .
The Aceto carmine technique is usually used for smear preparations. This technique helps in staining the chromosome in the nucleus. The staining property of carmine is due to carminic acid.
Preparation of material :
Germinate broad bean (vicia fabia ) seeds in moist saw dust and cut about 5 mm long pieces of young roots germinating for about five days. or place onion bulbs above glass jars filled with water, leave for 3 to 4 days and when several roots have grown 1_2 cm long , remove the bulbs and cut off the terminal 1cm of the root.
If the experimental material is intended to be stored, it may be fixed using Carnoy’s Fixative. the roots may be placed in the fluid for 24 hours at room temperature and then washed with 90% ethyl alcohol and stored. The carnoy’s fixation can be prepared by mixing 1 part of glacial acetic acid with 3 parts of absolute ethyl alcohol.
The following steps should be added for the preparation of smear or squash and staining
- boil the root piece in water and place.
- place the root piece in a petri dish in Carmine solution
- take out the root piece place it on glass slide. then take two needles and while holding the end of the root with one, use the other needle to split the root into several longitudinal stripes
- place the roots slip on the fresh slide in a drop of carmine, and cover with a cover glass.
- cover the cover glass with the piece of filter paper and press hard drown without any sideways movements to reduce the tissue to smear or squash i.e. one cell layers.
- Examine the slide under a microscope and identify different stages of mitosis.
Aceto Carmine stain preparation:
Mix 45 ml of glacial acetic acid with 55 ml of distilled water. Heat to boiling and add 0.5 gm to 1 gm of carmine dye . Shake well and filter when cool.