The invention of the microscope is attributed to Zacharias Janssen in the late 16th century (around 1590). While there's some debate about the exact inventor, Janssen's work is widely accepted.

Theodor Schwann was a German physiologist who made significant contributions to cell theory. He is known for his discovery of the Schwann cells in the nervous system and for his work on the cell theory, which states that all living things are composed of cells.