theodor Schwann work alone to develop the cell theory?
No, Theodor Schwann did not work alone to develop the cell theory. The cell theory was actually developed by multiple scientists, including Matthias Schleiden and Rudolf Virchow, in addition to Theodor Schwann.
Matthias Schleiden, a German botanist, first proposed that plants are made up of cells in 1838. Following this, Schwann, a German physiologist, extended Schleiden's ideas and proposed that animals are also composed of cells. Schwann published his findings in 1839.
However, it was Rudolf Virchow, a German physician, who added the third component to the cell theory in 1855. Virchow proposed that all cells arise from pre-existing cells, thus emphasizing the concept of cell division and the continuity of life.
Together, the contributions of Schleiden, Schwann, and Virchow formed the basis of the cell theory, which is now a fundamental concept in biology. It states that all living organisms are composed of cells, cells are the basic units of structure and function in living organisms, and cells arise from pre-existing cells through cell division.
There is some vandalism on that page, especially in dates.
Here is a better source
http://scienceworld.wolfram.com/biography/Schwann.html