Onion Root Mitosis

Allium root tip

by Joseph C. Rossi

It is common to see photomicrographs of onion root cells when demonstrating how cell division takes place in plants. Onions have larger chromosomes than most plants and stain dark. The chromosomes are easily observed through a compound light microscope.

The cells pictured below are located in the apical meristem of the onion root. The apical meristem is an area of a plant where cell division takes place at a rapid rate.


Phases of plant cells division:

1) Interphase is considered the first and last stage of plant cell division. It is the stage in which the cell is growing in size and replicating its DNA in preparation for division. The nucleus is apparent.

2) Prophase. During Prophase the nuclear envelope starts to break down and all the chromosomes start to coil up in the center of the cell.

3) Metaphase is the middle stage at which point all the chromosome pairs line up in the center of the cell along spindle fibers that pull to either side of the cell.

4) Anaphase. The spindle fibers become shorter and pull each chromosome pair apart to the opposite ends of the cell.

5) Telophase. The final stage of cell replication.The nuclear envelope is reformed. Cytokinesis takes place. A new cell wall is created down the center and two daughter cells are formed.




1) Interphase
2) Prophase
3) Metaphase
4) Anaphase
5) Telophase

All photomicrographs captured at approximately 160X

with a Nikon D1X

Lighting technique:

Kohler illumination

Equipment used to photograph the onion root:

Nikon Optiphot microscope

Nikon Plan Apochromatic 40X objective

Nikon Apochromatic sub stage condenser




I am a Student at Rochester Instutuite of Technology studing in the Biomedical Photographic Communications Department.

email : Jcr0920@rit.edu

Return to index of articles by students on the 'Principles and techniques of photomacrography' course, November 2004,
Biomedical Photographic Communications (BPC) program at the Rochester Institute of Technology (RIT).

Article hosted on Micscape Magazine (Microscopy-UK).