This image shows the internal structure of a mouse liver, helping to understand this complex organ. Sinusoids – blood vessels – can be seen as pink structures running through the tissue. These contain red blood cells and Kupffer cells, which are specialist macrophages of the liver. Liver cells, or hepatocytes, shown in brown, are arranged in plates surrounding the sinusoids. Bile is secreted into the passages known as canaliculi, shown as green channels. They are dilated intercellular spaces between hepatocytes, and bile flows through them en route to the small intestine. (Image: Jackie Lewin) [NewScientist]