General embryology :Formation of neural tube

 Formation of neural tube

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The notochord induces the overlying ectoderm to differentiated into neuro-ectoderm, which forms the neural tube and the process of formation of  the neural tube is known as neurulation.

Steps of formation of neural tube

1.       The ectoderm overlying the notochord changes and forms neuro-ectoderm

2.       These cells proliferate to form a thick plate called neural plate which extends in midline from primitive knot to prochordal plate / buccopharyngeal membrane.

3.       the margin of the neural plate gets elevated due to the growth of para-axial mesoderm which is situated two sides of notochord.

4.       these elevated structure is known as neural folds, and some cells differentiate into neural crest cells

5.       neural groove is developed in between two neural folds

6.       Gradually, the neural folds approach each other in the midline, where they fuse and neural crest cells start to disassociate from neuro ectoderm.

7.       Fusion of neural folds begins in the cervical region (fifth somite) and give rise neural tube which is open at both ends known as anterior and posterior cranial neuropores

8.       Neural tube is  communication with amniotic cavity through the anterior and posterior cranial neuropores

9.       Gradually the neural tube proceeds cranially and caudally and

10.    anterior cranial neuropore close at 25^th  days becomes lamina terminalis and if it is fail to close it result upper neural tube defects (NTDs) e.g.  anencephaly

11.   posterior cranial neuropore close at 28^th days and if it is fail to close it result lower  neural tube defects (NTDs) e.g.  spina bifida

12.   the rostral part of neural tube becomes the adult brain and the caudal part becomes adult spinal cord

13.   the lumen of the neural tube gives rise to the ventricular system of brain and central canal of spinal cord.