The exact role of a tissue in an organism depends on what types of cells it contains. For example, the endothelial tissue that lines the human gastrointestinal tract consists of several cell types.

There are many different types of cells in plants. Each type is specialised to do a particular role and ensures that the organism functions as a whole. The root hair cell has a large surface area ...

perkinsii, an ancestral species of protist. This unicellular organism ... of their life cycle and comprise at least two distinct cell types, a surprising phenomenon for this type of organism.