This image shows the heterogeneity in the content of lysosomes near the plasma membrane between two hepatocytes and near the bile canaliculus (not visible in this field). Some of the lysosomes contain residues resulting from partial digestion of lipids and some of these are more electron dense than others. Not only does the content of lysosomes vary depending on the cell type, but also physiological conditions, and even amongst lysosomes within an individual cell. Also in the field are mitochondria, rough endoplasmic reticulum, and the cell membrane. This image is part of a set of two; both images are identical, but on one of the twins, organelles are labeled by name. Small blocks of liver tissue were fixed in 4% osmium tetroxide in 0.1 M cacodylate buffer pH 7.4 for 2 hours. The tissue was dehydrated and embedded in Epon. Sections were stained for 1 minute with ethanolic uranyl acetate and then alkaline lead citrate for 5 minutes. Original resource was provided as a 3.25 x 4 inch lantern slide by George E. Palade; original is in the Palade Collection, University of California, San Diego. Digitization process: Lantern slide scanned at 1200 dpi in TIFF format, labeled in Photoshop then reduced to 600 dpi TIFF file (3500 x 2705 pixels) prior to conversion to JPEG2000 format.