Polarised light micrograph of cholesterol crystals. Cholesterol (formerly known as cholesterine) is essential to all animal life. It is an important component of cell walls and is a precursor in the synthesis of steroid hormones, bile acid and Vitamin D. It can either be absorbed directly from food or manufactured by the body. Cholesterol exists in two different forms; low density lipoprotein (LDL) and high density lipoprotein (HDL). Excessive levels of LDL increase the risk of heart disease, while HDL performs a protective role. Magnification: x68 at 10cm wide.