Induction (biology)

As induction refers to the initiation of a development-physiological process. In embryonic development, it is an important factor for the differentiation and determination of a germ ( embryo ).

Embryonic and hormonal induction

The trigger for the induction is a morphogenetic movement that brings the cell structures into a different chemical or physical environment. They come into contact with the signal from the inductor (signal generator) and differentiate themselves in a very specific way under its influence. There are various ways of doing this. If there is close contact between the cell and the inductor, one speaks of embryonic induction . This requires special receptor molecules on the cell surface. Induction can also be triggered by more extensive chemical signals from the inductor. This is called hormonal induction . There is also the possibility that the same inductors lead to different induction processes. This is due to the different competencies of the cell.

For example, toads - epidermis forms structures toads mouth with an inductor, said pig -Epidermis pig mouth structures formed with the same inductor. Different concentrations of the inductor can also lead to different induction processes.

Example: In the case of the tadpole, an inductor leads to a breakdown in the tail region, to a build-up in the leg region and to a remodeling of cell structures in the eye region due to different concentrations of the inductor.

Induction is the specific differentiation of a germ caused by the inductor. The genetic code is converted and made usable by the cell in a manner controlled by the inducer ( gene expression ).

history

The phenomenon of induction was discovered while researching the determination of the various cotyledons . One wanted to find out whether all cotyledons are determined at the same time. For this purpose, a piece of presumptive notochord - mesoderm tissue was taken and placed in another germ layer ( ectoderm ) ( transplantation attempt ) or between two germ layers ( insertion attempt ). It was found that not only the notochord formed from the chordamesoderm tissue, but that other cell structures in the vicinity were also influenced. A Siamese twin with two chordas formed from the germ. The chordamesoderm tissue was already determined. The neighboring tissue was differentiated into notochord tissue by induction:

Representation of the transplant attempt (a) and the insertion attempt (b)

Induction chain

In an induction chain, several inductions take place one after the other, whereby first induced tissue in turn develops induction capacity itself and thus functions as an inductor for the next link in the chain.