At the same time, Nehemiah Grew published his work on tissues. He believed that a woven mass of fibres was what made up living material. It wasn’t till the 1840’s that cells were recognised as the basic units of life. This was expressed by Matthias Schleiden and Theodore Schwann in their work, Cell Theory, which was published in 1839. Cell Theory was the conclusion that all plants were made up of cells and the same could be said about the organisation of animals. This was of considerable biological significance because it suggested that there was a common denominator for all living matter.
There are two main types of microscope which are used for the study of cells. These are the electron microscope and the light microscope. Electron microscopes are usually considered to be the best option for a scientist because they provide the highest levels of magnification. It was the electron microscope which revolutionised our understanding of cell structure. It has the ability to magnify up to 500 times more than the light microscope, and it revealed the ultrastructure of a cell. There are many advantages of the electron microscope. Such as, they have huge powers of magnification and resolution. However, they also come with many disadvantages. For example, all specimens placed under an electron microscope are examined inside of a vacuum – this means that air scatters the electrons and makes the image fuzzy. Also, this type of microscope is expensive. They need to maintain a constant internal vacuum, along with a constant temperature and pressure. They are very hard work to maintain.
The light microscope is somewhat different. It was invented before the electron microscope and so limited the observations of the fine detail within cells that scientists could carry out. Before this, however, it opened up a new world of structural detail for a biologist. Like the electron microscope, the light microscope has many advantages and disadvantages. Under a light microscope parts of living plants and animals can be seen directly. This means that you can compare prepared slides with living tissue. However, light microscopes have limited powers of resolution and magnification. Also, because of preservation and staining, what is seen under the microscope may be a result of preparation, rather than the real tissue.
Thanks to the development and the continuous improvements made to microscopes, knowledge about cells has progressed a long way. Without it, we would not have been able to develop our understanding of how cells work.
