Immature Bone

00:02 I just first of all want to point out the difference between mature bone and immature bone.

00:09 On the right-hand side, you can see an image, taken through a young person's bone. And I am going to describe the difference between immature bone and mature bone and I'll have a little competition for you to do. As I describe the difference between these two types of bone, I want you to try and identify mature bone on this image and immature bone. I am not going to label it for you. So we are going to have a little competition here, see if you can do it. Well, we often call immature bone, bundle bone or woven bone, and that is because there is no lamella formed as you see in compact mature bone. The lamellae are rings or straight parallel lamellael sheaths of bone matrix laid down by the osteoblasts and then enclosed by osteocytes. They form the osteon in compact bone that are described in our previous lecture.

01:24 When you see mature bone lying side by side, immature bone as you see here, the immature bone has a different cell concentration. The cells are cluttered close together and there's more of them per unit area. The cells or the osteocytes in mature bone tend to follow straight lines and those lines follow the lamellae formed in the lamella or mature bone. Also, immature bone has a lot more amorphous ground substance in it. So it stains more basophilic as opposed to adult bone or mature bone that is more eosinophilic because it changes its matrix composition. And these changes in staining you see in sections like this, which is stained with normal hemotoxin and eosin. So do you think you can now identify in this section, immature bone and mature bone. I am sure you will identify the dark reddish or bright reddish components being mature bone because you can see the osteocytes lined up, and the more basophilic components of the matrix in the immature bone enable you to make this differentiation.

02:53 So well done!