Kidney. Proximal Convoluted Tubule. Trypan Blue Stock Photo

Proximal convoluted tubes in a kidney of an experimental animal injected with Trypan blue, a vital stain. Trypan blue, filtered through the glomerulus, is reabsorbed as it passes through the proximal convoluted tubule and incorporated into endocytic vacuoles to which the lysosomes subsequently fuse. These vacuoles appear on the image as blue spots in the cytoplasm of the cells in the convoluted