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)
tire noun [C] (WHEEL). âº a ârubber âring, usually âfilled with âair, that âfits around the âwheel of a âcar, âbicycle, or other âvehicle: Most âcars now have âradial tires. (Definition of tire from the Cambridge Academic Content Dictionary Â© Cambridge University Press).ire noun [C] (WHEEL). âº a ârubber âring, usually âfilled with âair, that âfits around the âwheel of a âcar, âbicycle, or other âvehicle: Most âcars now have âradial tires. (Definition of tire from the Cambridge Academic Content Dictionary Â© Cambridge University Press).