Question

how many different cells there are in the human body.

Answer 1

It is very difficult to count off certain types of cells in a multicellular organism like in human. we can not count them directly through microscope as is very impractical to do so.
So, scientist could only make an estimation regarding the total number of cells in human body.
the exact number of cells in a human body can not be estimated. There are more than 200 types of cells in human body
According to a recent research made by a team of scientist of Italy the total number of cell ranges between 10¹² and 10¹⁶