Now the logic is beginnig to emerge. Dynamic instability is a mechanism that allows the cytoskeleton to build structures with an exploratory strategy, and the power of this strategy can be evaluated by considering how many different structures it can give origin to. The answer is astonishing: the number of different structures that cytoskeletons can create depends only upon the choice of anchoring molecules, and is therefore potentially unlimited.
It is the anchoring molecules (that strangely enough biologists call accessory proteins) that determine the form that cells can have in space and the movements that they can perform. The best proof of this enormous versatility is the fact that the cytoskeleton was invented by monocellular eukaryotes, but later was exploited by metazoa to build completely new structures such as the axons of neurons, the miofibrils of muscles, the mobile mouths of macrophages, the tentacles of killer limphocytes and countless other specializations.
We conclude that dynamic instability is a means of creating an endless stream of cell types with only one common structure and with the choice of a few anchoring molecules. But this is possible only because there is no necessary relationship between the common structure of the cytoskeleton and the cellular structures that the cytoskeleton is working on.
The anchoring molecules (or accessory proteins) are true adaptors that perform two independent recognition processes: microtubules on one side and different cellular structures on the other side. The resulting correspondence is based therefore on arbitrary rules, on true natural conventions that we can refer to as the cytoskeleton codes.

The compartments

The plasmatic membrane of bacteria can be compared to a cellular “skin” because it contains structures that synthesize its molecules in loco, just as a true skin contains the cells that continually renew it.