The human body contains over 200 unique cell types. Further still, numerous human body cell types can be split further into different varieties of cell, within the cell type. For example, we can split white blood cells into several distinct varieties including lymphocytes and macrophages (a type of phagocytes).

Despite many common features present across a range of human body cell types, 5 each type is also specialised (sometimes very highly) to carry out its specific function. Although the majority of cell types contain the same organelles, the number of certain organelles that each cell type contains can differ significantly. A notably large number of mitochondria are present in muscle cells, for example, and hormone-secreting cells in the pancreas have distinctly large amounts of rough endoplasmic reticulum.

Interestingly, the amount of a certain organelle is not always fixed during a cells 'life' and this was observed by scientists looking at the cells in the tails of tadpoles. As a tadpole develops into a frog, its tail is gradually reabsorbed into the main body of the tadpole. The scientists found that the number of lysosomes in the tail cells actually increased as the tadpole matured.