Cells: similarities and differences
Eukaryotic cells (and animal cells in particular) come in a wide range of shapes and sizes. In humans, for instance, red blood cells are around 7 micrometres (µm) in diameter, whereas megakaryocytes (which are responsible for platelet production) are 10–15 times bigger – about 100 µm in diameter. Different cell types in the same animal look different because they have different functions in the body – their specialised shapes and contents help them to do their jobs better.
The Science Ideas and Concepts articles Animal cells and their shapes and Cell organelles give further information about the differences between different animal cell types.