Cell: Definition, Types, Functions and Division (Part 2)
History and Origin A cell was defined as “ unit of biological activity delimited by a semi permeable membrane and capable of self-reproduction in a medium free of other living systems” by Loewy and Siekevitz (1963) . The study of cell has been made possible with the help of light microscope. Robert Hooke (1665) with the help of light microscope discovered that a section of cork is made up of small cavities surrounded by firm walls. He used the term “cell” for the first time to describe his investigations on the “texture of a piece of cork”. Later on A. Van Leeuwenhoek (1632-1723) observed various unicellular organisms and cells like bacteria, protozoan’s, red blood cells and sperm etc. He observed nucleus in some erythrocytes and all this was made possible with the improved microscopes. In 1809, Mirble M. stated that all plant tissues are composed of cells. In the same year, importance of cells in living organisms was described by J.B. L...