Chromosomes were first observed in the dividing cell of :

Explanation

When scientists first observed chromosomes in the dividing cells of salamander larvae, they noticed these thread-like structures that contained genetic material. These chromosomes play a crucial role in carrying and passing on genetic information from one generation to the next. They contain DNA, which carries the instructions for building and functioning of living organisms. By studying chromosomes, scientists have been able to gain valuable insights into genetics and how traits are inherited. It's pretty incredible how these tiny structures hold the blueprint of life.