Aging Of The Functional Morphology Of The Bruchs Membrane

Investigations have shown that the areas of reduced perfusion have an elevated threshold of adaptation to the dark and a pattern of changes similar to those observed in cases of Vitamin A deficiency. The second group of studies arrived at the same conclusions by demonstrating that Sorsby's dystrophy, an illness that causes loss of central vision at a young age, is characterized by the presence of rich deposits of lipids in the Bruch's membrane. The conclusion of these studies is that the loss of vision function results from the accumulation of deposits in the Bruch's membrane, which acts as a barrier to the elimination of catabolites as well as the arrival of nutrients to the retina.

Pauleikoff et al. (1990) examined the immunohisto-chemical and ultrastructural properties of the Bruch's membrane of 30 human eyes of ages 1 to 95 years. The results of the three age groups from 0 to 30, from 31 to 60, and from 60 onward show that there is an age-related progressive increase in the lipid content of the Bruch's membrane. In the young age group, none of the stains caused any coloration. In the second age group, 8 out of 10 samples, and in the over-60 age group all the samples, were colored with Bromine-Sudan Black B, with and without acetone; only a few samples from the second and third age groups showed strong coloration, whereas only samples from the third age group showed coloration with Oil Red O (see Figure 67.10).

Moore and Clover (2001) were the first to measure the permeability of the Bruch's membrane to

Figure 67.10 Light microscopy of the Bruch's membrane belonging to donors aged 18 (top), 47 (middle), and 75 (bottom). The three figures on the left are stained with Bromine-Acetone-Sudan Black B, those on the right are stained with Oil Red O. It can be seen that the intensity of staining with both systems increases with age, which shows the progressive age-related accumulation of lipids (magnification 400x; calibration bar 10 mm).

Figure 67.10 Light microscopy of the Bruch's membrane belonging to donors aged 18 (top), 47 (middle), and 75 (bottom). The three figures on the left are stained with Bromine-Acetone-Sudan Black B, those on the right are stained with Oil Red O. It can be seen that the intensity of staining with both systems increases with age, which shows the progressive age-related accumulation of lipids (magnification 400x; calibration bar 10 mm).

macromolecules, the first to determine the maximum dimensions of molecules that can cross the Bruch's membrane, and the first to ascertain the effects of age on the barrier that the Bruch's membrane represents against the flow of substances other than water. Age has three effects on the permeability of macromolecules across the Bruch's membrane. First, the exclusion based on molecular mass reduces gradually; second, in the eighth decade of life the membrane selectively impedes the passage of specific macromolecules, not on the basis of their molecular weight, but on other criteria. Finally, in the ninth decade, the membrane becomes an impermeable barrier to any molecule.

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Blood Pressure Health

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