<Tr> <Th> Code </Th> <Td> TE E5. 14.1. 0.0. 0.1 </Td> </Tr> <Tr> <Td_colspan="2"> Anatomical terminology (edit on Wikidata) </Td> </Tr> <P> In the developing chordate (including vertebrates), the neural tube is the embryo's precursor to the central nervous system, which comprises the brain and spinal cord . The neural groove gradually deepens as the neural folds become elevated, and ultimately the folds meet and coalesce in the middle line and convert the groove into the closed neural tube . In humans, neural tube closure usually occurs by the fourth week of pregnancy (28th day after conception). The ectodermal wall of the tube forms the rudiment of the nervous system . The centre of the tube is the neural canal . </P> <P> The neural tube develops in two ways: primary neurulation and secondary neurulation . </P>

When does the neural tube develops in a fetus