Haversian Canal Essay

Bone is a specialised, strong, flexible connective tissue and is the main component of the adult skeleton. Unlike hyaline and fibrocartilage, bone is supplied with nerves and blood vessels. Epiphyseal veins carry the blood away from the long bones of the body and periosteal arteries, which are also accompanied by nerves, carry blood to the bones. It provides support and gives the structural framework to the body, it acts as a protective cover for internal organs such as the heart, brain and lungs, it provides sites of attachment for muscles, it stores minerals such as calcium and phosphate and it contains cavities where bone marrow produces blood cells. Bone is made up of two main components, cells and the bone matrix. There are four different types of cells in the bone; osteogenic, osteocytes, osteoblasts and osteoclasts of which
The Haversian canal, Haversian vessel, Haversian lamellae and the cement line of the osteon can be seen. The Haversian canal can be seen as a circular opening at the centre of the osteon. The function of these canals is to carry the blood vessels and nerves throughout the bone. In some Haversian canals, the remains of some nerve fibres and blood vessels can be seen like in this canal pictured. When these remnants are present it is called a Haversian vessel.
Surrounding the Haversian vessel, or canal, is concentric lamellae which are layers of mineralised matrix. These lamellae are pink in colour which shows the eosin dye of H&E is staining this structure. This means that the lamellae of the osteons are acidophilic structures. The last structure of the osteon that can be seen in this figure is the cement line. This is a thin line that surrounds the entire osteon. It is purple in colour which shows the haemotoxylin dye of H&E is staining the cement line. This is turn means that this part of the osteon is a basophilic