A second important point is that the semantic theory of the cell is not merely an addition of the ribotype concept to the classical duality of Johannsen. The self-replicating machine described by Von Neumann is also a system which introduces a ribotype (a universal constructor) between genotype and phenotype (Mange and Sipper, 1998), but is not a valid model of a living cell, because Von Neumann’s genotype must contain a complete description of its phenotype. Von Neumann’s machine, in other words, is not an epigenetic system.
The semantic theory, instead, has its very foundation in the idea that a cell is an epigenetic system, and states that organic codes and organic memories are indispensable precisely because only they can make a phenotype more complex than its genotype. If the living cell is an epigenetic system, in conclusion, then it is bound to have organic codes, and it is bound therefore to be a semantic system.

The semantic theory of embryonic development

After fertilization and a first round of cell divisions (cleavage), the early embryo begins what is probably the most important phase of its development (gastrulation) by separating the cells which remain in contact with the outside world (ectoderm) from those that bury themselves inside the body (endoderm and mesoderm). The ectoderm is the first “skin” of the embryo, and the primary purpose of any skin is to form an impermeable barrier around the body (if water could enter and exit freely, the size and the shape of a body would change erratically according to the surrounding degree of humidity).
The ectoderm ensures that the inner space of a body is sharply distinct from the outside world, and all forms and shapes that we find in that inner space are entirely due to endogenous processes of three-dimensional organization. And the same is true for every single cell. The plasmatic membrane controls virtually everything that is passing through, and is for a cell what ectoderm is for an embryo: the structure that sharply divides the inner space from the outer world, thus giving the inner system the freedom to build its own structures in complete autonomy.