Stereological changes in the capillary network of the aging dorsal lateral geniculate nucleus.

In this work we studied the effect of aging on the capillaries of the dorsal lateral geniculate nucleus in 3-, 18-, 24-, and 28-month-old rats. The parameters analyzed were the capillary profile density, capillary volume fraction, length and surface area per unit volume, and capillary average diameter. The quantitative analysis showed in all parameters an increase between 3 and 18 months, and a significant decrease in capillary volume fraction (-18.75%) and diameter (-5.5%) between 18 and 24 months. No changes from 24 months onwards were observed. The increase observed in capillary profile density and capillary volume fraction between 3 and 18 months may indicate an increase of the capillary network. Furthermore, we observed an increase in the length and surface area per unit volume, which we interpret as an expansion of the exchange surface between blood and nerve tissue. The reduction in the capillary parameters that takes place between 18 and 24 months is slight, and may indicate the onset of decline characteristic of aging.