The quantitative morphological changes in neurons and glia during the aging process were analyzed in the different cortical layers, grouped as I, II-IV, V, and VI, of the frontal cortex of the rat. The parameters analyzed were cortical volume, neuronal density, glial density, and neuronal soma and nucleus areas. No changes with age were found in the volume of the layers, in neuronal density (with the exception of layer I), or in the area of the neuronal soma. However, older animals showed a 10 to 20% increase in glial density, depending on the layer studied. In addition, there was an age-related decrease in the area of the neuronal nucleus in layers II-IV, V, and VI. These results support the idea that the aging frontal cortex undergoes structural changes that may be involved in the morphological basis of memory and cognitive impairments characteristic of aging.

The frequency of astrocytes, microglia plus oligodendrocytes, and pericytes displaying nuclei was analyzed and quantified in 160-µm-wide strips of the parietal cortex (Par1 region) from young and aged Wistar rats. The study was performed on two groups of rats aged 3-4 and 32-36 months. Quantifications of the glial cell types and pericytes were made in 1-µm-thick sections stained with toluidine blue. Ultrathin sections were also made to analyze the ultrastructural features of these cells during aging. Astrocytes and pericytes increased in number by about 20% and 22%, respectively, with age. These increases were most significant in layers II-IV and V for both cellular types. Clusters of astrocytes were common in these layers of aging rats. The ultrastructural analysis also indicated changes in all cell types that stored inclusions and vacuoles with age, which were particularly abundant in microglial cells. End-feet astrocytes and pericytes surrounding the vascular wall also contained vacuoles and inclusions, and consequently the vascular wall increased in thickness. In conclusion, the aging process increased astrocyte and pericyte populations, but not microglia plus oligodendrocyte populations, in the rat parietal cortex. Although no significant change in nuclear size could be observed in any cell type, all glial cells as well as pericytes underwent morphological ultrastructural changes. These modifications may result from the need to correct possible homeostatic imbalances during aging.

Background: Different changes in neuronal and glial population of the aging brain have been described; however, the degree and extent of these changes are controversial. This study evaluates the quantitative and cytomorphometric effects of aging on neuronal and glial populations in the parietal cortex of the rat.Methods: The study was performed in two groups of rats aged 4-6 and 30-32 months. Cortical volume, neuronal density, glial density, and neuronal area, and shapes of the soma and nucleus were analyzed in cortical layers I, II-IV, V, and VI using serial sections stained with cresyl-fastviolet, and quantitative morphometric techniques.Results: No changes with age were found in volume of the cortex or neuronal density. Glial density increased significantly (mean for all layers 17%) in older rats. Layers II-IV, V, and VI showed an age-related decrease in the area of the neuronal soma. Neuronal shape, as revealed by the major/minor diameter ratio, also showed a decrease in old rats but only in layer II-IV. Nuclear area decreased with age only in layer VI.Conclusions: The stability of neuronal density together with the increased number of glial cells and the changes in neuronal soma size suggest that aged-related cognitive impairment could be a consequence of neuronal dysfunction rather than actual neuronal losses.

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In this study we explored possible applications of the da Vinci system in approaching the skull base at optic chiasm level on two cryopreserved cadavers, using an entirely transoral robotic technique (TORS). We used a standard 12 mm endoscopy and 8 mm terminals. Bone drilling was performed manually. The da Vinci system is equipped with very good illumination and 3D viewing, thus providing excellent vision and great maneuverability even in the less accessible areas of the skull. Our experience demonstrates that an entirely transoral skull base robotic approach to this complex anatomical region has many advantages as compared to traditional techniques.