Experimental Brain Research

, Volume 68, Issue 2, pp 329–338 | Cite as

Altered morphology of dorsal lateral geniculate nucleus neurons in methylazoxymethanol acetate induced micrencephaly

  • K. Ashwell


The morphology of neurons in the dorsal lateral geniculate nucleus (dLGN) of rats made micrencephalic by prenatal exposure (E13 or E15) to the cytotoxic agent, methylazoxymethanol acetate, has been examined in Golgi impregnations. Type B neurons were unaffected by exposure on either day while type A neurons showed significant reductions in both soma diameter and dendritic field area following exposure on E15, but not E13. These results indicate that target deprivation of type A neurons (by destruction of neurons in the granular and supragranular layers of the occipital cortex with exposure on E15) has a more significant effect on development of type A neurons than the direct cytotoxic action of the agent on precursors of dorsal lateral geniculate nucleus neurons in the fetal thalamus (seen with exposure on E13 in a previous study). The findings are significant because they indicate that the indirect effects of cytotoxic teratogens on the developing brain (acting via the target dependence of some neuronal classes) may cause structural und functional alterations in the brain which differ from those predicted on the basis of the direct action above. This study also shows that the percentage of relay neurons in the dorsal lateral geniculate nucleus is unaffected in animals exposed to the agent on E15, despite pronounced reductions in neuronal numbers and changes in relay neuron morphology.

Key words

Dorsal lateral geniculate nucleus Micrencephaly Microcephaly Rats Methyl-azoxymethanol acetate 


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  1. Abercrombie M (1946) Estimation of nuclear population from microtome sections. Anat Rec 94: 239–247Google Scholar
  2. Altman J, Bayer SA (1979) Development of the diencephalon in the rat. IV. Quantitative study of the time of origin of neurons and the internuclear chronological gradients in the thalamus. J Comp Neurol 188: 455–472Google Scholar
  3. Ashwell KWS (1986a) The rat lateral geniculate nucleus and occipital cortex in experimental micrencephaly. Neurosci Lett [Suppl] 23: S30Google Scholar
  4. Ashwell KW (1986b) The morphology of dorsal lateral geniculate nucleus neurons in micrencephalic rats: disordered differentiation following target deprivation. Proc Aust Physiol Pharmacol Soc 17: 47PGoogle Scholar
  5. Ashwell KW (1987) Direct and indirect effects on the lateral geniculate nucleus neurons of prenatal exposure to MAM Ac. Dev Brain Res (in press)Google Scholar
  6. Brauer K, Schober W (1973) Qualitative und quantitative Untersuchungen am Corpus geniculatum laterale (Cgl) der Laborratte. I. Zur Struktur des Cgl unter besonderer Berücksichtigung der Golgi-Architektonik. J Hirnforsch 14: 389–398Google Scholar
  7. Brauer K, Schober W, Winkelmann E (1979) Two morphologically different types of retinal axon terminals in the rat's dorsal lateral geniculate nucleus and their relationship to the X-and Y-channel. Exp Brain Res 36: 523–532Google Scholar
  8. Ebbesson SOE (1970) Selective silver-impregnation of degenerating axons and their synaptic endings in non-mammalian species. In: Nauta WJH, Ebbesson SOE (eds) Contemporary research methods in neuroanatomy. Springer, Berlin Heidelberg New York, pp 132–161Google Scholar
  9. Grossman A, Lieberman AR, Webster KE (1973) A Golgi study of the rat dorsal lateral geniculate nucleus. J Comp Neurol 150: 441–466Google Scholar
  10. Halasz P, Martin P (1984) A microcomputer based system for semi-automatic analysis of histological sections. Proc R Microsc Soc 19: 312PGoogle Scholar
  11. Johnston MV, Coyle JT (1982) Cytotoxic lesions and the development of transmitter systems. Trends Neurosci 5: 153–156Google Scholar
  12. Juraska JM, Fifkova E (1979) An electron microscope study of the early postnatal development of the visual cortex of the hooded rat. J Comp Neurol 183: 257–268Google Scholar
  13. Lund RD, Mustari MJ (1977) Development of the geniculocortical pathway in rats. J Comp Neurol 173: 289–296Google Scholar
  14. Hiromu M, Spatz M, Laqueur GL (1972) Quantitative changes with age in the DNA content of methylazoxymethanolinduced microencephalic rat brain. J Neurochem 9: 297–306Google Scholar
  15. Mesulam M (1982) Principles of horseradish peroxidase neurohistochemistry and their applications for tracing neural pathways — axonal transport, enzyme histochemistry and light microscopic analysis. In: Mesulam M-M (eds) Tracing neural connections with horseradish peroxidase. John Wiley, New York, pp 1–51Google Scholar
  16. Ohara PT, Lieberman AR, Hunt SP, Wu J-Y (1983) Neural elements containing glutamic acid decarboxylase (GAD) in the dorsal lateral geniculate nucleus of the rat; immunohistochemical studies by light and electron microscopy. Neuroscience 8: 189–211Google Scholar
  17. Ottersen OP, Storm-Mathisen J (1984) GABA-containing neurons in the thalamus and pretectum of the rodent. Anat Embryol 170: 197–207Google Scholar
  18. Peters A, Proskauer CC, Feldman ML, Kimerer L (1979) The projection of the lateral geniculate nucleus to area 17 of the rat cerebral cortex. V. Degenerating axon terminals synapsing with Golgi impregnated neurons. J Neurocytol 8: 331–357Google Scholar
  19. Parnavelas JG, Mounty ES, Bradford R, Lieberman AR (1977) The postnatal development of neurons in the dorsal lateral geniculate nucleus of the rat: a Golgi study. J Comp Neurol 171: 481–500Google Scholar
  20. Rafols JA, Valverde F (1973) The structure of the dorsal lateral geniculate nucleus in the mouse. A Golgi and electron microscopic study. J Comp Neurol 150: 303–332Google Scholar
  21. Scheibel ME, Scheibel AB (1978) The methods of Golgi. In: Robinson RT (eds) Neuroanatomical research techniques. Academic Press, New York, pp 89–114Google Scholar
  22. Sefton AJ, Dreher B (1985) Visual system. In: Paxinos G (eds) The rat nervous system, Vol 1. Academic Press, Sydney, pp 169–221Google Scholar
  23. Sugita S, Otani K (1983) Quantitative analysis of the lateral geniculate nucleus in the mutant microphthalmic rat. Exp Neurol 82: 413–423Google Scholar
  24. Sumitomo I, Iwama K (1977) Some properties of intrinsic neurons of the dorsal lateral geniculate nucleus of the rat. Jpn J Physiol 27: 717–730Google Scholar
  25. Webster MJ, Rowe MH (1984) Morphology of identified relay cells and interneurons in the dorsal lateral geniculate nucleus of the rat. Exp Brain Res 56: 468–474Google Scholar
  26. Werner L, Kruger G (1973) Qualitative und quantitative Untersuchungen am Corpus geniculatum laterale (Cgl) der Laborratte. III. Differenzierung von Projektions und Interneuronen im Nissl-Präparat und deren Topographie. Z Mikrosk Anat Forsch 87: 701–729Google Scholar

Copyright information

© Springer-Verlag 1987

Authors and Affiliations

  • K. Ashwell
    • 1
  1. 1.Department of AnatomyUniversity of SydneySydneyAustralia

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