Microscopic Investigation and Identification of Mitotic Stages Using Onion (Allium cepa) and Onion Spring (Allium fistulosum)

Abstract

Mitosis is a fundamental process in plant growth and development because it governs the production of new cells in meristematic tissues. Examining its stages provides insights into genetic stability and cellular behavior, which are relevant to agriculture, crop improvement, and environmental monitoring. Although cytological studies using Allium species are well established, there is continued value in demonstrating how classical staining methods, such as acetocarmine, effectively visualize mitotic events in educational and basic laboratory settings. This study aimed to identify and describe the stages of mitosis in onion (Allium cepa) and spring onion (Allium fistulosum) root tips using acetocarmine-stained squash preparations. Fresh root tips were hydrolyzed in hydrochloric acid, stained with acetocarmine, and examined under a compound light microscope. The observed mitotic stages were documented based on chromatin morphology and nuclear characteristics. Both species exhibited similar observable mitotic features under the staining and microscopic conditions used, with clear visualization of prophase, metaphase, and telophase, identified by chromatin condensation, chromosome alignment, and nuclear reformation, respectively. Anaphase was not observed, likely due to its brief duration relative to the other phases. Overall, the results demonstrate that acetocarmine staining provides reliable visualization of major mitotic stages, although it lacks sufficient resolution to distinguish individual chromosomes. These findings confirm that simple cytological techniques remain effective tools for demonstrating mitosis in instructional and introductory research contexts. Future studies may employ DNA-specific stains, digital imaging, and larger sample sizes to capture short-lived stages and enable quantitative analysis.