Page 14 - SAAT BIOLOGY PART 1

SAAT BIOLOGY MR.MOHAMED ELGAYAR MRPROF.NET
The ectoderm layer gives rise to nervous tissue and skin.

The mesoderm gives rise to muscle, the circulatory system,

the excretory system, and in some species of animals the

respiratory system, The endoderm gives rise to the

digestive organs and digestive tract lining.

The innermost layer is the endoderm, followed by the

mesoderm and then the outer layer, the ectoderm.

The pseudocoelom develops between the mesoderm and

endoderm; the coelom develops within the mesoderm.

In protostomes, the mouth develops from an opening in the

gastrula.

Segments are repeated similar components of a body plan,

which are able to evolve different functions, for example

mouth parts, and legs, that can operate independently

increasing the flexibility of the organism.

MRPROF.NET MR.MOHAMED ELGAYAR MRPROF.NET@GMAIL.COM 13