Calretinin neurons in human medial prefrontal cortex (areas 24a,b,c, 32?, and 25)
✍ Scribed by Gabbott, Paul L.A.; Jays, Paul R.L.; Bacon, Sarah J.
- Publisher
- John Wiley and Sons
- Year
- 1997
- Tongue
- English
- Weight
- 725 KB
- Volume
- 381
- Category
- Article
- ISSN
- 0021-9967
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✦ Synopsis
The calcium-binding protein calretinin (CR) is present in a subpopulation of local-circuit neurons in the mammalian cerebral cortex containing g-aminobutyric acid. This light microscopic investigation provides a detailed qualitative and quantitative morphological analysis of CR-immunoreactive (CR 1 ) neurons in the medial prefrontal cortex (mPFC; areas 24a,b,c, 328, and 25) of the normal adult human.
The morphology of CR 1 neurons and their areal and laminar distributions were consistent across human mPFC. The principal organisational features of CR 1 labelling were the marked laminar distribution of immunoreactive somata and the predominantly vertical orientation of labelled axon-like and dendritic processes. Several types of CR 1 neurons were present in layer 1, including horizontally aligned Cajal-Retzius cells. In layers 2-6, CR 1 neurons displayed a variety of morphologies: bipolar cells (49% of CR 1 population), vertically bitufted cells (35%), and horizontally bitufted cells (3.5%). These neuron types were mainly located in layer 2/upper layer 3, and their dendritic processes were commonly aspiny and sometimes highly beaded. Aspiny (8%) and sparsely spiny multipolar (5%) CR 1 neurons were also found. The mean somatic profile diameter of CR 1 cells was 11.6 6 0.3 µm (mean 6 S.D).
CA 1 puncta formed pericellular baskets around unlabelled circular somatic profiles in layers 2/3 and around unlabelled pyramidal-shaped somata in layers 5/6. The somatic sizes of these unlabelled cell populations were significantly different. Immunolabelled puncta were also found in close contact with CR 1 somata.
Cortical depth distribution histograms and laminar thickness measurements defined the proportions of the overall CR 1 cell population in each layer: 7% in layer 1, 78% in layers 2/3, 14% in layers 5/6, and 1% in the white matter. In the tangential plane, CR 1 neurons were distributed uniformly at all levels of the cortex. By using stereological counting procedures on immunoreacted Nissl-stained sections, CR 1 neurons were estimated to constitute a mean 8.0% (7.2-8.7%) of the total neuron population in each cortical area. These data are compared with similar information obtained for the mPFC in monkey and rat (Gabbott and Bacon [1996b]