What keeps the cells of multi cellular organisms stuck together?


I remember from high school biology that cells form tissues and then from these tissues organs are created, etc.

However what’s not clear for me is: What stops a cell tissue from totally collapsing back to a clump of cells? Why animals, plants and even some fungi don’t just… Melt?

In: 7

It’s called adhesion. Cells have proteins called cell adhesion molecules that cause them to stick together on the molecular level.

[Cadherin](https://en.wikipedia.org/wiki/Cadherin) and other [cell adhesion molecules](https://en.wikipedia.org/wiki/Cell_adhesion_molecule) like it connect the cell membranes of neighbouring cells. Outside the cells, there is something called the [extracellular matrix](https://en.wikipedia.org/wiki/Extracellular_matrix). That’s where stuff like collagen and hyaluronic acid exists to give structural integrity.

Highschool biology casually ignores all of that because it only has a limited amount of time to teach the basics of what possibly is the most complex natural science.

There are three things that all assist in anchoring cells to their surroundings. The first is the extracellular matrix (ECM), the network of material such as collagen that gives structure and support to most tissues. The second is cell adhesion molecules, or CAMs, which act as a glue to bind the cells to the ECM and to each other. The third is cell junctions, large specialized protein complexes which allow for communication and transport between cells while also providing adherence to each other and the ECM. Cell junctions come in a few different types, each with special purposes.

The question has different as wer depending on the type of cell – plant or animal.

Our own cells has protein complexes located in the membrane which connects the cells to each other as a form of short hands holding together. Depending on the protein these contacts can be water tight or very lose.
Some of our cells produce extra cellular materials – stiff building blocks that pushed out of the cells and into the area around and in between the cells.

These things combined makes it possible for tissue to keep it’s shape.

Plant cells are a little different from animal cells as they consist of a cell membrane (as animal cells) AND a cell wall which is rigid and strong

There are things called Desmond ones hemidesmosomes and gap junctions that hold everything together it’s like title zippers lining the cells