Microscopes and the Discovery of Cells

The first microscope;

It is believed that the first “true” microscope was invented in 1590 by father and son, Hans and Zaccharias Janssen.

It was a compound microscope (more than one lens).

Specimens could be enlarged, but the microscope was not very powerful, and didn’t produce a very clear image.

Discovery and naming of the cell;

In 1665 Robert Hooke described the small openings in a sliver of cork bark as pores, or cells (rooms).

The name “cell” is still being used today.

By 1674, Anton Van Leeuwenhoek invented his own simple microscope.

The single lens of his microscope could magnify clearly, up to about 270 X.

In 1674 he gave the first description of protozoa, and then nine years later (1683), he identified bacteria.

He called the small organisms animalcules.

Robert Brown is first to describe the cell nucleus in 1833.

Cell Theory; Matthias Schleiden (botanist) and Theodor Schwann (zoologist) proposed the first two statements of the cell theory in 1838.

The cell theory states that:

1. All organisms are made from one or more cells.

2. The cell is the basic unit of structure and organization of organisms.

3. Cells only arise from pre-existing cells.

1855 Rudolf Virchow proposed the third statement of the cell theory.

The first transmission electron microscope (TEM) is built in 1931. Allows magnification of about 500,000 times actual size.

Compound Light microscopes improve during the late 1800’s and early 1900’s. They are now capable of magnification at a power of 1500 X

Used to study structures within a cell.

Also in the 1850’s, Virchow realized that the nucleus is responsible for cell division.

First commercial scanning electron microscope (SEM) in 1965.

Scans surface of cell, to give three dimensional image.

Allows magnification of about 20,000 X.

The scanning tunneling microscope (STM) was introduced in the 1980’s.

It magnifies up to one hundred million X (100,000,000).

It allows scientists to view atoms on the surface of an object.

Hans and Zaccharias Janssen- This is their 1608 version of a compound microscope.

Robert Hook’s ← compound microscope

and his drawing of cork cells ↓

Van Leeuenhoek microscope and illustrations of animalcules.

Scanning electron microscopes

The head of an ant →

← Transmission electron microscope

Interior structures of a cell ↓

← Scanning Tunneling Microscope

Iron atoms on a copper surface →