14.1 The origin of muscle tissue



Genesis of the middle germinal layer (mesoderm)


With only a few exceptions the musculature stems from mesoblast cells that – for their part – come originally from a population of epiblast cells (ectoderm cells), which immigrate via the primitive streak 6-11 between the hypoblast and the remaining epiblast cells. They thus form a middle germinal layer, the mesoderm layer.



Fig. 1 - The streaming in of epiblast cells via the primitive streak
in stage 8, ca. 23 days
 Legenda

1
2
3
4
Prechordal plate
Primitive nodes
Primitive groove with entrance into the axial canal (canalis neuro-entericus)
Primitive streak

Fig. 1
The left image shows an embryo dorsally. The epiblast cells stream in via the primitive streak and nodes and form the mesoderm layer. In the right image the embryo is shown in a median longitudinal section. The region of the prechordal plate is colored in red. The area where the cardiogenic plate arises is indicated by a red arrow.




Meer info

Detailed information about the structures in this diagram.


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