L12 from the macrophage hits the cd4 positive T cell converting it to a helper th1 type cell and the th1 cells secret into interferon gamma that gives the macrophage and epithelial tissue a sight and appearance. Granuloma is distinct from granulation tissue. Granulation tissue is the initial phase of repair when you are forming a scar. Granulation tissue consist of fibroblasts and the fibroblast deposit type III collagen. It consist of capillaries and the capillaries provide the nutrients and then the granulation tissue also consists of myofibroblast and this contract down the wound. I will talk about this in a little more detail in a few slides but let’s see a picture first. Let’s look at a picture first.
This is granulation tissue and you can see that this granulation tissue is comprise of these blood vessels and in addition to these blood vessels because you can clearly that there is this deposition of collagen and the presence of some of these fibroblast which are also part of the granulation tissue. Again this is the classic finding of granulation tissue.
It’s important to recall or remember or to learn that eventually that granulation tissue will produce a scar, you see that’s the end result. Like I said granulation tissue is the earlier form of what eventually become a scar. One of the key features that distinguishes granulation tissue from a scar is that when you have a scar the type III collagen of the granulation tissue is replaced with type I collagen. Maybe this is a good point to take a step back and just remind ourselves of collage and its different subtypes. I'm going to actually clear up the board here and give you a white board.
Can you remember a few important points of collagen? Number one, one important collage is type I collagen. And you remember what type me collagen it’s see in? Its seen in bone and one of the ways that people remember that is that when you think about bone, it has a word -one within it, so that reminds you of...