Comparison of the size of pericytes of the retinal capillaries in the normal and diabetic state.

The sizes of pericytes and aneurysms were measured in washed and unfixed flat autodigest preparations of retinae from normal and diabetic Wistar albino rats kept under observation for up to 12 months. The weight of the lens and lens basement membrane (capsule) was also measured at the time animals were killed. It was found that a very significant increase in the numbers of larger pericytes occurred in the diabetic animals. However, the overall number of pericytes plus aneurysms in the diabetic animal was not greater than the number of pericytes seen in normal animals. No dilatations greater than the diameter of a retinal were seen in normal vessels, so anything greater was considered to be an aneurysm. A very significant correlation exists between the size of the lens and the size of the pericytes in each animal and suggests a common growth relationship. These significant correlations occur in both the normal and diabetic state. Moreover, for a given size of lens, the number of larger pericytes is much increased in the diabetic state. It is suggested that this may be due to the increased extensibility of basement membrane which occurs in the diabetic state with weakening of the capillary wall. This is compensated for by an increase in the size of the surrounding pericyte.