The Department of Biology at the College of Education for Pure Sciences organized a training course on (How to extract chromosomes from bone marrow), delivered by the lecturer, Dr. (Razia Najm Abd). The course aimed to introduce participants to the nature of chromosomes, their types and structure, and to introduce the types of numerical and structural chromosomal imbalances and some of the genetic diseases resulting from them. The course also included an explanation of the method of extracting chromosomes from the bone marrow of albino mice using KCl solution, and learning about how to extract chromosomes from the bone marrow of albino mice. He called on those interested to pay attention to such topics in order to practice studying the chromosomal imbalances that can occur in some diseases.