Layer Specific Erythrocyte Density in the Somatosensory Cortex of Mice, and Its Age-related Changes

Laminar variations in erythrocyte density in the somatosensory cortex of young mice and senescent mice were compared. The mouse brains were fixed, frozen, frontally sliced at 20 micrometers, and double-stained for DAB and cresyl violet. The sliced cortices were cytoarchitectonically divided into 5 laminar regions, layer 1, layers 2 and 3, layer 4. layer 5, and layer 6. Each region was photographed and translated into digital image data and the area of each region was measured by NIH-image 1.55 on a Macintosh powerbook 180c. The area of erythrocytes on the photograph was measured in the same way. Erythrocyte density was represented by the area ratio (erythrocyte-area) / (laminar-area). The results were as follows, (1) Young and senescent mice each had a distinct distribution pattern of erythrocytes in the cortical layers. (2) In the young mice, layer 4 had the highest erythrocyte density, and the density decreased toward layer 1 or layer 6. In the senescent mice, layer 4, layer 5 and layer 6 had almost the same density, and the density decreased toward layer 1. (3) The density of layer 4 was significantly differed between the 2 groups. (4) There was no significant difference between the 2 groups in erythrocyte density through all layers of the somatosensory cortex. These findings demonstrated age-related changes in erythrocyte density in the somatosensory cortex. The reduced erythrocyte density is related to decrease in cerebral blood flow.

大脳皮質

体性感覚皮質

barrel

毛細血管

血流