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!