Transmission Electron Microscopic Findings of Lacrimal Gland Acinar Cells Induced by In Vivo Dry Eye

ABSTRACT

PURPOSE: To determine the change in lacrimal gland (LG) acinar cells induced by in vivo dry eye (DE). METHODS: Six to 8-week-old (C57BL/6) mice were placed in a controlled environment chamber at <20% humidity for 2 weeks, and a control group was bred in a normal environment. After these 2 weeks of dry eye (DE) induction, the mice were sacrificed and their LGs were collected. Lacrimal gland acinar cell organelle structures were observed with Transmission Electron Microscopy (TEM). TEM images were analyzed using the Image J program. RESULTS: The size of the LGs of DE-induced mice decreased compared to those of normal mice. Terminal deoxynucleotidyl transferase dUTP Nick End Labeling (TUNEL) staining was negative in DE-induced LGs. Under the TEM, the endoplasmic reticulum (ER) lumen was dilated and the lumen density increased in DE-induced mice. Additionally, cell organelles were surrounded by elongated ER lumens. The mitochondrial structure was destroyed and the number of vacuoles increased in the LGs of DE-induced mice. CONCLUSIONS: Structural changes of the LG developed due to DE induction. This suggests that the detailed mechanisms of these changes were ER stress and autophagy. However, there were no definite signs of apoptosis in the acinar cells of the DE-induced LGs. These findings are regarded as an important clue of the pathogenesis of non-Sjogren-type dry eye.