Abstract
Abstract: :
Purpose: The purpose of the present study is to analyze elements and their localization of the secretory granules in the palpebral conjunctiva of RICO (rats with inherited hypercholesterolemia) rats by energy dispersive x–ray analyzer (EDX), and to compare them with normal Wistar Kyoto rats. Materials and methods: We used six–month–old RICO rats and six–month–old Wistar Kyoto rats. Immediately after the palpebral conjunctivae were excised, they were frozen with slushy nitrogen and then put into liquid nitrogen. Ultra–thin sections were made with a cryo–ultramicrotome, freeze–evaporation–dryed, carbon–coated and observed under transmission electron microscope (TEM). Elements of the secretory granules in the palpebral conjunctiva of RICO rats were analyzed with EDX and compared them with those of normal Wistar Kyoto rats. Result: Under TEM, we observed the secretory granules of RICO rats and Wistar Kyoto rats. And we observed the high density area outside of the secretory granules of RICO rats. Na, Mg, P, S, Cl, K were detected in the secretory granules and in the area outside of secretory granules with EDX in RICO rats and Wistar Kyoto rats. EDX detected high peak of Ca in addition to Na, Mg, P, S, Cl, and K in the high density area outside of the secretory granules of RICO rats, but Ca was not detected in any area of Wistar Kyoto rats. Discussion: The methods we used in this study were able to preserve tissue morphology and elements analysis of conjunctiva. We suppose that there was no change in the element composition of the secretory granules of RICO rats and Wistar Kyoto rats. However the high electron density area outside of the secretory granules in RICO rats was observed, and calcium deposition in that area was seen. This may be related to hypercholesterolemia. Conclusion: The physical fixation, ultra–thin freeze– sectioning method and freeze– evaporation–drying method are useful for the detection of elements in ocular tissues.
Keywords: conjunctiva • microscopy: electron microscopy