Alterations in microvasculature are associated with atrophy of the stria vascularis in quiet-aged gerbils

Age-related changes in the integrity of the stria vascularis and its microvasculature were assessed in whole mount preparations of the gerbil cochlear lateral wall. Small focal regions containing few or no capillaries were present at the extreme ends of the stria vascularis in most 5-9 month-old gerbils. A few ears in this age range also contained small regions devoid of capillaries at the extreme basal end of the stria. These degenerate foci expanded in a systematic fashion toward the middle turn of the cochlea with increasing age. Gerbils aged 33 months or older exhibited a normal strial vasculature pattern only in portions of the middle and upper basal turns. The remainder of the stria in these older gerbils contained degenerate regions which showed both loss of capillaries and atrophy of strial marginal cells. Quantification via computer-aided image analysis confirmed that the areas of strial atrophy correlated well with the loss of strial capillaries at all ages. However, regions containing capillaries with decreased diameter were not necessarily accompanied by atrophic changes in marginal cells. The results suggest that degeneration of the stria vascularis begins prior to onset of auditory threshold shift and is preceded and possibly initiated by changes in the strial microvasculature.