Lipids (Lipid) is a general term for neutral fats, lipids and their derivatives, their common physical properties are insoluble in water, soluble in organic solvents (such as ethanol, ether, etc.), there are two main types of fat in the human body: 1, storage fats, such as neutral fats, mainly located in the subcutaneous, kidneys, pancreas and other parts of the body; 2, structural fats, such as lipids (phospholipids, glycolipids, cholesterol, etc.), mainly located in the cell, the Phospholipids (phospholipid) consists of glycerol, fatty acids and nitrogen-containing bases, is the main component of the cell membrane and intracellular membrane structure, phospholipids in the brain, neural tissues, bone marrow and liver and other tissues in the content of the larger, phospholipids can be divided into lecithin, ceruloplasmin and nerve sheath phospholipids of three kinds, show that phospholipids commonly used methods of acid hematoxylin red method, pyridine extraction method.

Phospholipid staining solution (acidic hematoxylin method), also known as Baker phospholipid staining solution, can make the phospholipids by the role of calcium retention can not enter the fixative solution, the Baker oxidation solution treatment, so that the phospholipids and metal ions into an insoluble phospholipid chelates, acidic hematoxylin staining and then the formation of blue-black complex, phospholipids, nerve sheath phospholipids were blue-black.