ABSTRACT
Cytology is a branch of biology that deals with the study of cells, chromosomes, and other cell organelles including their structure, function, and formation. Robert Hooke coined the term cell in 1665 after observing a piece of cork under a microscope, and with keen observations, Hooke perceived the structure to be "all perforated and porous, much like a honeycomb, but pores were not regular; yet it was not unlike a honey-comb in these particulars. Monumental progress in cytology was initiated shortly after the rediscovery of Mendel's laws of inheritance in 1900. Sutton reported the chromosomal basis of heredity. Numerous chemicals were tested for pretreatment and staining of the cells and chromosomes of plants, animals, and humans. Tjio and Levan determined the correct chromosome number of humans. Since human cytology has progressed at a much faster pace than plant cytology. The smear technique is routinely used for human chromosomes, while the squash technique is common for mitotic and meiotic plant chromosomes.
