Abstract
Dendritic spines are small protrusions extending from the dendrites of nerve cells, which bear the majority of synapses. In the past, researchers quantified spine density as the number of visible spines per estimated micrometre of dendrite. This estimate ignores all those spines hidden from view due to their position on the dendrite. Dendrites vary in diameter and the underestimation in some will be greater than others. Estimation of dendritic length is also subjective and difficult in those which are tortuous. The Felman & Peters (1979) geometrical equation takes account of these criteria and provides a method of estimating 'true' spine numbers which does not involve slow and laborious reconstruction. This study compares ratios derived from both methods of estimation (spine density 2:1) at three loci in three experimental groups. Mean values of dendritic diameters and spine dimensions show the major cause for variation in the ratios between loci to be the shaft diameter of the dendrite. However, the greater ratio for apical as compared with basal and oblique dendrites is not as great as expected, bearing in mind that apical dendrites are approximately 2.5 times larger than oblique and basal dendrites. Therefore the spine distribution may not be the same throughout the dendritic field. Estimations of spine density based on visible spine counts are quicker, easier and sufficient for comparisons within the same locus. 'True' estimates (spine density 2) are more accurate and should be used when comparisons are being made between loci, cell types and species.
Full text
PDF
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Chan-Palay V., Palay S. L., Billings-Gagliardi S. M. Meynert cells in the primate visual cortex. J Neurocytol. 1974 Nov;3(5):631–658. doi: 10.1007/BF01097628. [DOI] [PubMed] [Google Scholar]
- Colonnier M. Synaptic patterns on different cell types in the different laminae of the cat visual cortex. An electron microscope study. Brain Res. 1968 Jul;9(2):268–287. doi: 10.1016/0006-8993(68)90234-5. [DOI] [PubMed] [Google Scholar]
- Feldman M. L., Dowd C. Loss of dendritic spines in aging cerebral cortex. Anat Embryol (Berl) 1975 Dec 31;148(3):279–301. doi: 10.1007/BF00319848. [DOI] [PubMed] [Google Scholar]
- Feldman M. L., Peters A. A technique for estimating total spine numbers on Golgi-impregnated dendrites. J Comp Neurol. 1979 Dec 15;188(4):527–542. doi: 10.1002/cne.901880403. [DOI] [PubMed] [Google Scholar]
- GRAY E. G. Electron microscopy of synaptic contacts on dendrite spines of the cerebral cortex. Nature. 1959 Jun 6;183(4675):1592–1593. doi: 10.1038/1831592a0. [DOI] [PubMed] [Google Scholar]
- Horner C. H., O'Regan M., Arbuthnott E. Neural plasticity of the hippocampal (CA1) pyramidal cell--quantitative changes in spine density following handling and injection for drug testing. J Anat. 1991 Feb;174:229–238. [PMC free article] [PubMed] [Google Scholar]
- McConnell P., Berry M. The effects of undernutrition on Purkinje cell dendritic growth in the rat. J Comp Neurol. 1978 Jan 1;177(1):159–171. doi: 10.1002/cne.901770111. [DOI] [PubMed] [Google Scholar]
- Peters A., Kaiserman-Abramof I. R. The small pyramidal neuron of the rat cerebral cortex. The perikaryon, dendrites and spines. Am J Anat. 1970 Apr;127(4):321–355. doi: 10.1002/aja.1001270402. [DOI] [PubMed] [Google Scholar]
- Riley J. N. A reliable Golgi-Kopsch modification. Brain Res Bull. 1979 Jan-Feb;4(1):127–129. doi: 10.1016/0361-9230(79)90067-4. [DOI] [PubMed] [Google Scholar]
- Riley J. N., Walker D. W. Morphological alterations in hippocampus after long-term alcohol consumption in mice. Science. 1978 Aug 18;201(4356):646–648. doi: 10.1126/science.566953. [DOI] [PubMed] [Google Scholar]
- Rutledge L. T., Duncan J., Cant N. Long-term status of pyramidal cell axon collaterals and apical dendritic spines in denervated cortex. Brain Res. 1972 Jun 22;41(2):249–262. doi: 10.1016/0006-8993(72)90501-x. [DOI] [PubMed] [Google Scholar]