Change in mast cell dimensions increases the profile number in sections of peripheral nerve of diabetic rats

Mast cell proliferation has been reported in peripheral nerves of streptozotocin diabetic rats. We examined the question by light microscopy using morphometric techniques including estimation of shape and size. After 4 weeks of diabetes the mast cell area in transverse sections was 32.7 +/- 7.0 microns 2 vs. 22.5 +/- 5.4 microns 2 in controls (P less than 10(2)). Mast cell profiles approximated to ellipses in longitudinal sections, the long diameter being 11.4 +/- 1.2 microns vs. 14.0 +/- 1.0 microns in controls (P less than 10(4)). Correspondingly, the profile number was increased (30 +/- 6%) in longitudinal sections and decreased in transverse sections (11 +/- 16%). The present study does not provide evidence for mast cell proliferation in peripheral nerves in experimental diabetes, and, furthermore, underlines the need of evaluation of dimensions in studies of particle numbers.