The cytology as a science. Cell theory, its value for medicine

The division of biology that study cell structure and functions is called cytology. The cell’s discovery is connected with the names of great scientists such as R. Hooke (1635-1703, M. Malpigi (1628-1694), N. Gru (1641-1712) etc. They were first to describe cell structure of many plants. A. Laevenhook (1632-1723) was a first exploring animal cell and cells of protozoa.

These researchers paid a lot of attention to cell membrane structure. Only Y. Purkinje (1787-1869) firstly concluded a nucleus being in a chicken egg and presence of fluid substance inside of the cell. He gave a name to this substance - protoplasm. In 1831 English botanists R. Brown (1773- 1858) and in 1836 Check scientists G. Valentin (18101883) were the first to find nucleuses in animal and plant cells.

In 1838 German botanists M. Shleiden (1804-1881) concluded that nucleus is most important pert of the cell and it is connected with new cells formation. As you can see from above, the cell discovering wasn’t a work of one scientist. It was a collective work during two centuries.

In 1839 German zoologist T. Schwan reported principles of cell theory, such as:
- A cell is a main structural unit of all animal and plant organisms.
- The growth, development and differentiation of animal and plant tissues are due to cell formation.
- A cell in appropriate limits is an individum, and organism is sum of them.
- New cells appear from cytoblastemm. The first three conclusions of T. Schwann are still correct. The fourth one isn’t.

Further development of cell theory is connected with a name of German scientist P. Virchow (1821-1902), who published his work “The cellular pathology” in 1858. P. Virchow was a first describing pathological process by materialistic way. He showed the connection of the pathological events with changes in cell structure. He corrected the fourth T. Schwann thesis and suggested a new one: Omnis cellula e cellula - each cell is from cell.

And today we still know only one way of cell appearance - by cell division. However, it might be considered that on early stages of life development cell appeared from non-cellular structures. The P. Virchow conclusion that there is no life outside of the cell is still correct. But others his conclusions weren’t proved by further science development. In particular, P. Virchow intensively developed incorrect conclusion of T.

Schwann about organism as a cell sum, from which it might be interfered that pathological process of organism is a sum of pathological processes in particular cells. P. Virchow and his fellows didn’t recognized the differences between part and total, observing organism without it historical development and environment. Assessing the P. Virchow’s “The cellular pathology” in general, it may be pointed that it was an important sign in a history of biology and medicine. And after slight correction, it made a basement for contemporary views to organism cell structure.

The formation of cell theory was completed on a base of new findings acquired from modem cell researches. Main statements of cell theory are:

1. All organisms are composed of one ore more cells, within which the life processes of metabolism and heredity occur.
2. Cells are the smallest living things, the basic unit of organization of all organisms.
3. Cells arise only by division of previously existing cell.
4. Cells of multicellular organisms are specialized in function and form tissues.
5. Cells of specialized tissues form organs.

The cell theory is a great generalization of XIX century. The creation of cell theory had a great value for development of materialistic view on life in all branches of biology and medicine.