Figure 6.

Meibum melting within the meibomian ducts of a mouse. A 12-μm cryosection of a mouse meibomian eyelid was prepared and studied in cross-polarized light with no compensator in the light path. The sample temperatures are indicated in each frame. Note the gradual disappearance of the lipid birefringence with the increase in the temperature of the sample. Most, if not all, birefringence is gone by 40°C to 45°C. After cooling of the sample to approximately 0°C, the birefringence was restored, albeit to a lesser degree than before. We attribute this to spreading of the lipid beyond its original location during the first melting cycle. Magnification: ×100; image size: 0.9 × 1.2 mm.