Morphological and electrophysiological characterization of layer III cells of the medial entorhinal cortex of the rat
Section snippets
Slice preparation
Horizontal slices (400 μm thick) from adult female Wistar rats (200–250 g) containing the hippocampus, entorhinal, perirhinal and temporal cortices (as described previously[8]) were cut using a Vibroslice (Campden Instruments, Loughborough, U.K.). Earlier in the study slices were also cut using a McIlwain tissue chopper. The slices were transferred to a standard interface chamber maintained at 34°C and perfused at a rate of 1.5–1.8 ml/min with artificial cerebrospinal fluid, containing (in mM):
Results
In this study we made stable recordings from 185 medial EC layer III cells. Forty were also identified morphologically and located at a range of positions within the medial EC relative to the cortical surface (mean 436.3±15.4 μm, range 300–587 μm). Across all cell types there was no significant difference in their positions (F3,34=1.8, P=0.16, one-way ANOVA). On the basis of the morphological characteristics of the subset of labelled cells, we broadly separated the cells into two groups, those
Discussion
We describe four different cell types within layer III of the medial EC. The morphological details of the recorded cells helped to classify the cells into two major groups on the basis of whether their axons reached deep layers heading towards the angular bundle or whether they remained within the EC. Based on the absence of spines, type 1 could be differentiated from type 2, 3 and 4 cells. Type 4 cells had a very characteristic axonal arborization which made them distinct from the other
Acknowledgements
We acknowledge support from the HFSP, SFB 515 and a Royal Society Exchange Program Fellowship to R.M.E.
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Present address: Department of Pharmacology, University of Oxford, Mansfield Road, Oxford, OX1 3QT, U.K.