Morphogenetic movements during cranial neural tube closure in the chick embryo and the effect of homocysteine


In order to unravel morphogenetic mechanisms involved in neural tube closure, critical cell movements that are fundamental to remodelling of the cranial neural tube in the chick embryo were studied in vitro by quantitative time-lapse video microscopy. Two main directions of movements were observed. The earliest was directed medially; these cells invaginated into a median groove and were the main contributors to the initial neural tube closure. Once the median groove was completed, cells changed direction and moved anteriorly to contribute to the anterior neural plate and head fold. This plate developed into the anterior neuropore, which started to close from the 4-somite stage onwards by convergence of its neural folds. Posteriorly, from the initial closure site onwards, the posterior neuropore started to close almost instantaneously by convergence of its neural folds. Homocysteine is adversely involved in human neural tube closure defects. After application of a single dose of homocysteine to chick embryos, a closure delay at the initial closure site and at the neuropores, flattening of the head fold and neural tube, and a halt of cell movements was seen. A possible interference of Hcy with actin microfilaments is discussed.

This is a preview of subscription content, log in to check access.

Access options

Buy single article

Instant unlimited access to the full article PDF.

US$ 39.95

Price includes VAT for USA

Subscribe to journal

Immediate online access to all issues from 2019. Subscription will auto renew annually.

US$ 199

This is the net price. Taxes to be calculated in checkout.

Fig. 1
Fig. 2
Fig. 3
Fig. 4
Fig. 5
Fig. 6


  1. Aerts LAGJM van, Blom HJ, Deabreu RA, Trijbels FJM, Eskes TKAB, Peereboom-Stegeman JHJC, Noordhoek J (1994) Prevention of neural tube defects by and toxicity of L-homocysteine in cultured postimplantation rat embryos. Teratology 50:348–360

  2. Afman LA, Blom HJ, Put NMJ van der, Straaten HWM van (2003) Homocysteine interference in neurulation: a chick embryo model. BDRA 67:421–428

  3. Bancroft M, Bellairs R (1975) Differentiation of the neural plate and neural tube in the young chick embryo. Anat Embryol 147:309–335

  4. Chapman SC, Collignon J, Schoenwolf GC, Lumsden A (2001) Improved method for chick whole-embryo culture using a filter paper carrier. Dev Dynamics 220:284–289

  5. Colas JF, Schoenwolf GC (2001) Towards a cellular and molecular understanding of neurulation. Dev Dynamics 221:117–145

  6. Copp AJ, Greene ND, Murdoch JN (2003) The genetic basis of mammalian neurulation. Nat Rev Genet 4:784–793

  7. Czeizel AE, Dudas I (1992) Prevention of the first occurrence of neural-tube defects by periconceptional vitamin supplementation. New Engl J Med 327:1832–1835

  8. Dardik R, Savion N, Gal N, Varon D (2002) Flow conditions modulate homocysteine induced changes in the expression of endothelial cell genes associated with cell-cell interaction and cytoskeletal rearrangement. Thromb Haemost 88:1047–1053

  9. Davidson LA, Keller RE (1999) Neural tube closure in Xenopus laevis involves medial migration, directed protrusive activity, cell intercalation and convergent extension. Development 126:4547–4556

  10. Epeldegui M, Pena-Melian A, Varela-Moreiras G, Perez-Miguelsanz J (2002) Homocysteine modifies development of neurulation and dorsal root ganglia in chick embryos. Teratology 65:171–179

  11. Ezin AM, Skoglund P, Keller R (2003) The midline (notochord and notoplate) patterns the cell motility underlying convergence and extension of the Xenopus neural plate. Dev Biol 256:101–114

  12. Gordon R (1985) A review of the theories of vertebrate neurulation and their relationship to the mechanics of neural tube birth defect review. J Embryol Exp Morphol 89:229–255

  13. Greene NE, Dunlevy LE, Copp AJ (2003) Homocysteine is embryotoxic but does not cause neural tube defects in mouse embryos. Anat Embryol 206:185–191

  14. Hamburger V, Hamilton HG (1951) A Series of normal stages in the development of the chick embryo. J Morphol 88:49–92

  15. Hansen DK, Grafton TF, Melnyk S, James SJ (2001) Lack of embryotoxicity of homocysteine thiolactone in mouse embryos in vitro. Reprod Toxicol 15:239–244

  16. Juriloff DM, Harris MJ, Tom C, Macdonald KB (1991) Normal mouse strains differ in the site of initiation of closure of the cranial neural tube. Teratology 44:225–233

  17. Keller R, Shih J, Sater A (1992) The cellular basis of the convergence and extension of the Xenopus neural plate. Dev Dynamics 193:199–217

  18. Kubova H, Folbergrova J, Mares P (1995) Seizures induced by homocysteine in rats during ontogenesis. Epilepsia 36:750–756

  19. Lawson T, Anderson H, Schoenwolf GC (2001) Cellular mechanisms of neural fold formation and morphogenesis in the chick embryo. Anat Rec 262:153–168

  20. Moephuli SR, Klein NW, Baldwin MT, Krider HM (1997) Effects of methionine on the cytoplasmic distribution of actin and tubulin during neural tube closure in rat embryos. Proc Natl Acd Sci USA 94:543–548

  21. Morriss-Kay G, Tuckett F (1985) The role of microfilaments in cranial neurulation in rat embryos: effects of short-term exposure to cytochalasin D. J Embryol Exp Morphol 88:333–348

  22. MRC Vitamin Study Research Group (1991) Prevention of neural tube defects: results of the medical research council vitamin study. Lancet 338:131–137

  23. Nagele RG, Lee HY (1987) Studies on the mechanisms of neurulation in the chick: morphometric analysis of the relationship between regional variations in cell shape and sites of motive force generation. J Exp Zool 241:197–205

  24. Nakatsu T, Uwabe C, Shiota K (2000) Neural tube closure in humans initiates at multiple sites: evidence from human embryos and implications for the pathogenesis of neural tube defects. Anat Embryol 201:455–466

  25. Put NMJ van der, Eskes TKAB, Blom HJ (1997) Is the common 677C->T mutation in the methylenetetrahydrofolate reductase gene a risk factor for neural tube defects? A meta-analysis. Q J Med 90:111–115

  26. Rafelski SM, Theriot JA (2004) Crawling toward a unified model of cell mobility: spatial and temporal regulation of actin dynamics. Annu Rev Biochem 73:209–239

  27. Rosenquist TH, Ratashak SA, Selhub J (1996) Homocysteine induces congenital defects of the heart and neural tube: effect of folic acid. Proc Natl Acd Sci USA 93:15227–15232

  28. Sadler TW (1998) Mechanisms of neural tube closure and defects. Mental Retard Dev Disab Res Rev 4:247–253

  29. Schoenwolf GC (1982) On the morphogenesis of the early rudiments of the developing central nervous system. Scan Electron microsc 1982/I:289–308

  30. Schoenwolf GC, Alvarez IS (1989) Roles of neuroepithelial cell rearrangement and division in shaping of the avian neural plate. Development 106:427–439

  31. Shum ASW, Copp AJ (1996) Regional differences in morphogenesis of the neuroepithelium suggest multiple mechanisms of spinal neurulation in the mouse. Anat Embryol 194:65–73

  32. Smith JL, Schoenwolf GC (1987) Cell cycle and neuroepithelial cell shape during bending of the chick neural plate. Anat Rec 218:196–206

  33. Steegers-Theunissen RPM, Boers GHJ, Trijbels FJM, Finkelstein JD, Blom HJ, Thomas CMG, Borm GF, Wouters MGAJ, Eskes TKAB (1994) Maternal hyperhomocysteinemia: a risk factor for neural- tube defects? Metabolism 43:1475–1148

  34. Straaten HWM van, Jaskoll T, Rousseau AMJ, Terwindt-Rouwenhorst EAW, Greenberg G, Shankar K, Melnick M (1993) Raphe of the posterior neural tube in the chick embryo-its closure and reopening as studied in living embryos with a high definition light microscope. Dev Dynamics 198:65–76

  35. Straaten HWM van, Janssen HCJP, Peeters MCE, Copp AJ, Hekking JWM (1996) Neural tube closure in the chick embryo is multiphasic. Dev Dynamics 207:309–318

  36. Straaten HWM van, Peeters MCE, Szpak KWF, Hekking JWM (1997) Initial closure of the mesencephalic neural groove in the chick embryo involves a releasing zipping-up mechanism. Dev Dynamics 209:333–341

  37. Straaten HWM, van Sieben I, Hekking JWM (2002) Multistep role for actin in initial closure of the mesencephalic neural groove in the chick embryo. Dev Dynamics 224:103–108

  38. Tuckett F, Morriss Kay GM (1985) The kinetic behaviour of the cranial neural epithelium during neurulation in the rat. J Embryol Exp Morphol 85:111–119

  39. Wallingford JB, Harland RM (2001) Xenopus dishevelled signaling regulates both neural and mesodermal convergent extension: parallel forces elongating the body axis. Development 128:2581–2592

  40. Ybot Gonzalez P, Copp AJ (1999) Bending of the neural plate during mouse spinal neurulation is independent of actin microfilaments. Dev Dynamics 215:273–283

Download references

Author information

Correspondence to Henny W. M. van Straaten.

Electronic supplementary material

Supplementary materials









Supplementary materials










Rights and permissions

Reprints and Permissions

About this article

Cite this article

Brouns, M.R., Afman, L.A., VanHauten, B.A.M. et al. Morphogenetic movements during cranial neural tube closure in the chick embryo and the effect of homocysteine. Anat Embryol 210, 81–90 (2005).

Download citation


  • Chick
  • Neurulation
  • Neuropores
  • Cell movements
  • Homocysteine