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.

And why are they permanent ... location and type. However, scars never fully disappear, because the jumbled tissue remains ...

Nucleic acid extraction from biological samples is inherently difficult to execute consistently across different tissue types. Some tissue matrices are fibrous, contained in protective cell walls, or ...