Refractive Information and Courses from MediaLab, Inc.
These are the MediaLab courses that cover Refractive and links to relevant pages within the course.
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| This suspicious form, seen in a scotch tape prep, measures 54 micro meters by 28 micro meters. | View Page |
| Granular Casts Granular casts are composed of plasma protein aggregates and cellular remnants. Granular casts appear as cylinders of coarse, or fine, highly refractive particles. Coarsely granular casts (yellow arrow) contain large, coarse dark yellow or dark brown granules. They are very irregular in shape as shown in this high power magnification under the brightfield microscope. A hyaline cast can be seen just to the left of the coarse granular cast (blue arrow). | View Page |
| Fine Granular Casts Fine granular casts contain small refractive granules. These casts appear gray or pale yellow under the brightfield microscope. A phase contrast view is seen here.
The presence of an occasional granular cast is not considered pathologic. | View Page |
| Waxy Casts Waxy casts appear as cylinders of smooth, highly refractive material. They are yellow, homogeneous and their ends may be square or broken off. Cracks may occur within the cast, giving it a segmented appearance. Waxy casts are believed by some to be the final stage of degeneration of the fine granules of granular casts. Since the granules need time to degrade, this finding implies localized nephron obstruction. Waxy casts are seen in chronic renal failure, and acute and chronic renal allograft rejection. Unusually broad waxy casts are known as renal failure casts. These very broad casts are created in the dilated tubules seen in end-stage renal disease. | View Page |
| Match the following: | View Page |
| Hyaline Casts Hyaline casts are the type most commonly seen in the urine sediment. A few hyaline casts may occasionally be found in normal urine, and hyaline casts may be seen after strenuous exercise, during fever, diuretic therapy. Pathologically, hyaline casts may be seen with congestive heart failure, and may be seen together with other types of casts in a variety of renal diseases. Hyaline casts have a refractive index similar to the urine in which they are suspended. For this reason, hyaline casts will appear almost invisible under brightfield microscopy, but are easily of seen by phase-contrast microscopy. | View Page |
| Phase-Contrast Microscopy Phase contrast is used to detect casts and mucus which have a very low refractive index and may be missed using brightfield microscopy. Phase contrast enhances the outlines of casts and mucus, making their detection much easier. | View Page |
| Supravital Stains Supravital stains are available for examining wet preparations or staining preserved slides. They increase the overall visibility of the elements by increasing the refractive index. Permanent slides can be made by using the cytocentrifugation technique and staining with Papanicolaou's stain to provide even more standardized sediment and uniform stain. | View Page |