Changes

==Introduction==

==Introduction==

The nervous system develops from ectoderm. Some of the ectoderm will also develop into the epidermis. Signalling factors from elsewhere in the embryo determine which parts of the ectoderm become neural tissue or epidermis.  

The nervous system develops from '''ectoderm'''. Some of the ectoderm will also develop into the ''epidermis''. Signalling factors from elsewhere in the embryo determine which parts of the ectoderm become neural tissue or epidermis.  

In the anterior part of the embryo the ectoderm forms the '''neural plate''', a flat layer of ectodermal cells lying directly above the node. The process of development from this neural plate to the nervous system is split into two parts; primary and secondary neuralation.

In the anterior part of the embryo the ectoderm forms the '''neural plate''', a flat layer of ectodermal cells lying directly above the node. The process of development from this neural plate to the nervous system is split into two parts; primary and secondary neuralation.