Stabilization of cholesterol in myelin with digitonin: observation with polarized light

Cholesterol can be preserved in tissues dehyrated for light microscopy by incorporating digitonin into glutaraldehyde fixation. Fresh and fixed frozen sections of rat sciatic nerve exhibit strong, radially positive birefringence when viewed with polarized optics. However, tissue fixed and dehydrated with standard methods for Epon embedding shows very weak radially positive birefringence. The use of digitonin with a variety of techniques generally permits retention of optical activity in embedded nerves. Such observations suggest a preservation of lipids (presumably cholesterol) in molecular orientations necessary to produce Maltese cross patterns.