The intracytoplasmic droplets can also originate from phagocyted material followed by an intensive lysozome digestion. This interference is a crystalline structure property, and is due to the presence of esterified cholesterol in a liquid crystal state. Naturally, cholesterol-free droplets are not birefringent. It is possible to stain the fat droplets with a suitable fat stain like Sudan, Fat Red 7B, and others. To our view, staining is of little use, since the birefringent criteria is easy to observe and that staining has a tendency to stain degenerated cells that are erroneously interpreted as oval fat bodies.
Some fat droplets lose their birefringent characteristics.
It is sometimes possible to correct the crystalline disorganization by gently heating the slide, followed by a rapid cooling. The nature of oval fat bodies is debated. For Schumann , the cell is an oval renal proximal tubular cell with a fat droplets filled cytoplasm. For Stamey , oval fat bodies are in fact macrophages also known as foam cells. The latter has proposed the use of the term oval fat macrophages.