Anatomy and Embryology

, Volume 156, Issue 1, pp 73–88 | Cite as

Ultrastructural observations on closure of the neural tube in the mouse

  • Jan A. G. Geelen
  • Jan Langman


The fusion of the neural walls in the cephalic part of mouse embryos varying in age from 9 to 20 somites was examined with the electron microscope. In the rhombencephalic region the rim of the neural wall was formed from outside inward by ectodermal surface cells, a row of flattened cells without surface projections and neuroepithelial cells. At the junction of the surface ectoderm and the flat cells were seen large projections containing a cytoplasmic matrix without organelles and previously referred to as “ruffles”. The initial contact between the walls was made by the large cytoplasmic arms and numerous finger-like projections interdigitating with similar projections from the opposite wall. The projections originated from the surface ectoderm and possibly neural crest cells. During further fusion the surface ectoderm cells formed dense membrane specializations, thus establishing a firm contact.

The initial contact in the mesencephalon was formed by extensions from the surface ectoderm and was followed by the formation of specialized membrane junctions, as seen between the surface ectoderm in the rhombencephalon. The neuroepithelial cells facing the gap between the neural walls with their apical ends made contact with the cells from the opposing wall by numerous finger-like projections but membrane specializations failed to develop.

The closing mechanism in the prosencephalon and anterior neuropore regions differed from the previous areas in that the initial contact was established by the neuroepithelial cells. Only after this contact had been formed did the surface ectoderm cells close the gap. In contrast with the other areas many phagocytosed particles were seen in the prosencephalon and in the region of the anterior neuropore. Many particles from degenerated cells were found inside healthy surrounding cells. Some of these particles contained nuclear material and cytoplasmic organelles.

Key words

Closure Development Mammalina embryo Neural tube Ultrastructure 


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. Bancroft, M., Bellairs, R.: Differentiation of the neural plate and neural tube in the young chick embryo. Anat. Embryol. 147, 309–335 (1975)Google Scholar
  2. Barson, A.J., Portch, P.A.: Scanning electron-microscopy of dysraphic human and chick spinal cord. Dev. Med. and Child Neurol. 16 (Suppl. 32), 152 (1974)Google Scholar
  3. Christie, G.A.: Developmental stages in somite and post-somite rat embryos, based on external appearance, and including some features of the macroscopic development of the oral cavity. J. Morphol. 114, 263–286 (1964)Google Scholar
  4. Edwards, J.A.: The external development of the rabbit and rat embryo. In: Advances in teratology. Vol. 3 (D.H.M. Woollam, ed.), pp. 239–263. New York: Academic Press 1968Google Scholar
  5. Farbman, A.I.: Electron microscope study of palate fusion in mouse embryos. Develop. Biol. 18, 93–116 (1968)Google Scholar
  6. Gaare, J.D., Langman, J.: Fusion of nasal swellings in the mouse embryo: Surface coat and initial contact. Am. J. Anat. 150, 461–476 (1977)Google Scholar
  7. Geelen, J.A.G., Langman, J.: Closure of the neural tube in the cephalic region of the mouse embryo. Anat. Rec. 189, 625–640 (1977)Google Scholar
  8. Gouda, J.G.: Closure of the neural tube in relation to the developing somites in the chick embryo (Gallus gallus domesticus). J. Anat. 118, 360–361 (1974)Google Scholar
  9. Greene, R.M., Kochhar, D.M.: Surface coat on the epithelium of developing palatine shelves in the mouse as revealed by electron microscopy. J. Embryol. Exp. Morph. 31, 683–692 (1974)Google Scholar
  10. Harris, A.K.: Cell surface movements related to cell locomotion. Ciba Foundation Symposia, Elsevier Amsterdam, N.S., 14, 3–26 (1973)Google Scholar
  11. Hay, D.A., Low, F.L.: The fusion of dorsal and ventral endocardial cushions in the embryonic chick heart: a study in fine structure. Am. J. Anat. 133, 1–23 (1972)Google Scholar
  12. Hayward, A.F.: Ultrastructural changes in the epithelium during fusion of the palatal processes in rats. Arch. Oral Biol. 14, 661–678 (1969)Google Scholar
  13. Hinrichsen, C.F.L., Stevens, G.S.: Epithelial morphology during closure of the secondary palate in the rat. Arch. Oral Biol. 19, 969–980 (1974)Google Scholar
  14. Karnovsky, M.J.: A formaldehyde glutaraldehyde fixative of high osmolarity for use in electron microscopy. J. Cell Biol. 27, 137A-138A (1965)Google Scholar
  15. Keyser, A.: The development of the diencephalon of the Chinese Hamster. Acta Anat. (Basel), Suppl. 59 (1972)Google Scholar
  16. Leblond, C.P., Bennett, G.: Elaboration of cell coat glycoprotein. In: The cell surface in development (A.A. Moscona, ed.), pp. 29–50. New York: John Wiley and Sons 1974Google Scholar
  17. Löfberg, J.: Fusion of neural folds and early migration of neural crest cells. A scanning and transmission study of the amphibian embryo. Doct. thesis, Uppsala (1974)Google Scholar
  18. Los, J.A., van Eijndthoven, E.: The fusion of the endocardial cushions in the heart of the chick embryo. Z. Anat. Entwickl.-Gesch. 141, 55–75 (1973)Google Scholar
  19. Luft, J.H.: The structure and properties of the cell surface coat. Int. Rev. Cytol. 45, 291–382 (1976)Google Scholar
  20. Marin-Padilla, M.: The closure of the neural tube in the Golden Hamster. Teratology 3, 39–46 (1970)Google Scholar
  21. Moran, D., Rice, R.W.: An ultrastructural examination of the role of cell membrane surface coat material during neurulation. J. Cell Biol. 62, 172–181 (1975)Google Scholar
  22. Portch, P.A., Barson, A.J.: Scanning electron microscopy of neurulation in the chick. J. Anat. 117, 341–350 (1974)Google Scholar
  23. Pratt, R.M., Greene, R.M.: The effects of Diazo-oxo-norleucine (DON) on development of the palatal epithelium in vitro: In: New approaches to the evaluation of abnormal embryonic development (D. Neubert and H.-J. Merker, eds.), pp. 648–658. Stuttgart: Georg Thieme Publishers 1975Google Scholar
  24. Pratt, R.M., Greene, R.M., Hassell, J.R., and Greenberg, J.H.: Epithelial cell differentiation during secondary palate development. In: Extracellular matrix influences on gene expression (H.C. Slavkin and R.C. Greulich, eds.), pp. 561–565. New York: Academic Press 1975Google Scholar
  25. Revel, J.P.: Scanning electron microscope studies of cell surface morphology and labeling, in situ and in vitro. In: Scanning electron microscopy/1974 (O. Jahari and I. Corvin, eds.), pp. 541–548. Chicago, Illinois: Ill. Inst. Technol. Res. Inst.Google Scholar
  26. Sadler, T.W.: Distribution of surface coat material on fusing neural folds of mouse embryos during neurulation. Anat. Rec., in press (1978)Google Scholar
  27. Schlüter, G.: Ultrastructural observations on cell necrosis during formation of the neural tube in mouse embryos. Z. Anat. Entwickl.-Gesch. 141, 251–264 (1973)Google Scholar
  28. Schroeder, T.E.: Neurulation in Xenopus laevis. An analysis and model based upon light and electron microscopy. J. Embryol. Exp. Morphol. 23, 427–462 (1970)Google Scholar
  29. Schenefelt, R.E.: Morphogenesis of malformations in hamsters caused by retinoic acid: relation to dose and stage at treatment. Teratology 5, 103–118 (1972)Google Scholar
  30. Souchon, R.: Surface coat of the palatal shelf epithelium during palatogenesis in mouse embryos. Anat. Embryol. 147, 133–142 (1975)Google Scholar
  31. Tarin, D.: Scanning electron microscopical studies of the embryonic surface during gastrulation and neurulation in Xenopus laevis. J. Anat. 109, 535–547 (1971)Google Scholar
  32. Waterman, R.E.: SEM observations of surface alterations associated with neural tube closure in the mouse and hamster. Anat. Rec. 183, 95–98 (1975a)Google Scholar
  33. Waterman, R.E.: Scanning electron microscopic observations of neural tube closure in the embryonic mouse and hamster. Anat. Rec. 181, 506 (1975b)Google Scholar
  34. Waterman, R.E.: Topographic changes along the neural fold associated with neurulation in the hamster and mouse. Am. J. Anat. 146, 151–172 (1976)Google Scholar

Copyright information

© Springer-Verlag 1979

Authors and Affiliations

  • Jan A. G. Geelen
    • 1
  • Jan Langman
    • 1
  1. 1.Department of AnatomyUniversity of VirginiaCharlottesvilleUSA

Personalised recommendations