The cellular composition of the marsupial neocortex
Article first published online: 19 APR 2014
Copyright © 2014 Wiley Periodicals, Inc.
Journal of Comparative Neurology
Volume 522, Issue 10, pages 2286–2298, 1 July 2014
How to Cite
Seelke, A. M.H., Dooley, J. C. and Krubitzer, L. A. (2014), The cellular composition of the marsupial neocortex. J. Comp. Neurol., 522: 2286–2298. doi: 10.1002/cne.23534
- Issue published online: 19 APR 2014
- Article first published online: 19 APR 2014
- Accepted manuscript online: 11 JAN 2014 01:25AM EST
- Manuscript Accepted: 7 JAN 2014
- Manuscript Revised: 22 NOV 2013
- Manuscript Received: 1 OCT 2013
- National Institutes of Health . Grant Number: F32 NS064792 (to A.M.H.S.), R21 NS071225 and R01 EY022987 (to L.A.K.), and T32 EY015387 (to J.C.D.)
- isotropic fractionation
In the current investigation we examined the number and proportion of neuronal and non-neuronal cells in the primary sensory areas of the neocortex of a South American marsupial, the short-tailed opossum (Monodelphis domestica). The primary somatosensory (S1), auditory (A1), and visual (V1) areas were dissected from the cortical sheet and compared with each other and the remaining neocortex using the isotropic fractionator technique. We found that although the overall sizes of V1, S1, A1, and the remaining cortical regions differed from each other, these divisions of the neocortex contained the same number of neurons, but the remaining cortex contained significantly more non-neurons than the primary sensory regions. In addition, the percent of neurons was higher in A1 than in the remaining cortex and the cortex as a whole. These results are similar to those seen in non-human primates. Furthermore, these results indicate that in some respects, such as number of neurons, the neocortex is homogenous across its extent, whereas in other aspects of organization, such as non-neuronal number and percentage of neurons, there is non-uniformity. Whereas the overall pattern of neuronal distribution is similar between short-tailed opossums and eutherian mammals, short-tailed opossum have a much lower cellular and neuronal density than other eutherian mammals. This suggests that the high neuronal density cortices of mammals such as rodents and primates may be a more recently evolved characteristic that is restricted to eutherians, and likely contributes to the complex behaviors we see in modern mammals. J. Comp. Neurol. 522:2286–2298, 2014. © 2014 Wiley Periodicals, Inc.