Distribution of Elastic Fibers in the Lacrimal Sac and Nasolacrimal Duct of Japanese Cadavers.

Purpose: To investigate the distribution of elastic fibers in lacrimal sac and nasolacrimal duct of Japanese cadavers. Methods: We examined 8 lacrimal sacs and nasolacrimal ducts of 7 Japanese cadavers (4 right sides, 4 left sides; 3 males, 4 females; average age of 89 years at death) that were preserved with 10% buffered formalin. The harvested specimens were transversely sectioned. All specimens were stained with Elastica van Gieson. Micrographs were taken, and then converted to white and black images, and the elastic fiber density of 4 locations (middle and upper levels of lacrimal sac, and middle and lower levels of nasolacrimal duct) was compared. Results: Elastic fibers showed greater distribution in the lamina propria, compared with the submucosal tissue, at all locations (p < 0.001). Elastic fiber density within the lamina propria at the middle lacrimal sac level (13.5% 4.3%) was similar to the density observed at the upper lacrimal sac level (13.2% +/- 2.3%, p = 0.87) and the lower nasolacrimal duct level (17.8% +/- 6.0%, p = 0.088), but was significantly greater than the density observed at the middle nasolacrimal duct level (9.5% +/- 3.8%, p = 0.0001). Conclusions: Elastic fibers in the lacrimal sac and nasolacrimal duct are primarily distributed in the lamina propria, with a greater density at the upper and middle lacrimal sac levels, and at the lower nasolacrimal duct level, compared with the middle nasolacrimal duct level. This distribution of elastic fibers likely reflects the magnitude of mechanical stress within the lacrimal drainage system.