The basic unit of Compact Bone is an  osteon , which is also known as a  Haversian System . Each Haversian System (unit) has a cylindrical structure that consists of four parts: 1  A central tube called a Haversian Canal, which contains blood vessels and nerves.2  The Haversian Canal is surrounded by alternate layers of:here are two main types of bone tissue, compact bone and spongy bone. Individual bones in the body can be formed from both of these types of bone tissue. The diagram on the right shows the physical structure of a typical  long bone .
Definition of roe 1: the eggs of a fish especially when still enclosed in the ovarian membrane 2: the eggs or ovaries of an invertebrate (such as the coral of a lobster)
noun. verb. The definition of a die is a small marked cube used in games. An example of die is what is rolled when playing backgammon. Die is defined as to stop living, existing or fade away. 1  An example of die is pulling a plant out of the ground by its' roots.