Figure 2.
Tubule deposits co-localize with stellate cells and consist of microspheres that contain calcium and phosphate. (A,C) Bright field and (B,D) epi-fluorescent micrographs (right) of native preparations of anterior Malpighian tubules from flies expressing GFP in principal (A,B) or stellate cells (C,D). Alizarin Red is used to stain for calcium (arrow points to collecting duct, *marks calcium in distal tubule). Scanning electron microscopic (SEM) images of anterior Malpighian tubules from a fly cultured on P30 for 30 days (70X, E; 900X, F), followed by energy-dispersive X-ray-spectroscopy (EDX) microanalysis in G of an individual microsphere shown in the inset (2700X, H).