Neurulation in the Normal Human Embryo

  1. Gregory Bock and
  2. Joan Marsh
  1. Ronan O'Rahilly and
  2. Fabiola Müller

Published Online: 28 SEP 2007

DOI: 10.1002/9780470514559.ch5

Ciba Foundation Symposium 181 - Neural Tube Defects

Ciba Foundation Symposium 181 - Neural Tube Defects

How to Cite

O'Rahilly, R. and Müller, F. (2007) Neurulation in the Normal Human Embryo, in Ciba Foundation Symposium 181 - Neural Tube Defects (eds G. Bock and J. Marsh), John Wiley & Sons, Ltd., Chichester, UK. doi: 10.1002/9780470514559.ch5

Author Information

  1. Institut für Anatomie und Spezielle Embryologie, Universität Freiburg, Freiburg, Switzerland

Publication History

  1. Published Online: 28 SEP 2007

ISBN Information

Print ISBN: 9780471941729

Online ISBN: 9780470514559



  • neurulation;
  • human embryo;
  • neuropores;
  • differentiation;
  • neural ectoderm


The neural groove and folds are first seen during stage 8 (about 18 postovulatory days). Two days later (stage 9) the three main divisions of the brain, which are not cerebral vesicles, can be distinguished while the neural groove is still completely open. Two days later (stage 10) the neural folds begin to fuse near the junction between brain and spinal cord, when neural crest cells are arising mainly from the neural ectoderm. The rostral (or cephalic) neuropore closes within a few hours during stage 11 (about 24 days). The closure is bidirectional; it takes place from the dorsal and terminal lips and may occur in several areas simultaneously. The two lips, however, behave differently. The caudal neuropore takes a day to close during stage 12 (about 26 days) and the level of final closure is approximately at future somitic pair 3 1, which corresponds to the level of sacral vertebra 2. At stage 13 (4 weeks) the neural tube is normally completely closed. Secondary neurulation, which begins at stage 12, is the differentiation of the caudal part of the neural tube from the caudal eminence (or end-bud) without the intermediate phase of a neural plate.