Specification (biology)

In Biologie of the development the specification can be of three types.

Autonomous

There are no influence of the cells or fabrics nearby. If a blastomère is removed, the corresponding part on the embryo is missing. It is noted that the cells are specified in a very early way often before their migration.

The identity of the cell will be to him given by cytoplasmic determinants which are set up at the latest during segmented. One finds that in the invertebrate primarily which has a mosaic Développement.

Syncitiale

In the insects especially the specification is syncitiale. There is an interaction between cytoplasmic compounds of maternal origin and the cores in syncitium before the cellular formation of the membranes. When there is cellularisation the cells are already given. It is the transition blastuléenne.

Conditioned or conditional

To become cell is imposed by interactions with the environment. Nothing is fixed at the beginning. The relative positions of the cells are decisive during the development embryologic. The early ablation of a blastomère can be compensate by the close blastomères. One speaks about Développement to regulation. In this model the cellular rearrangements, the movements cellular accompany the specification.

This mechanism exists at all the species but it is dominating at the Vertébré S.

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