List the cells that form bone tissue.

The skeletal system of beings, especially human beings, is a pretty simple, and yet complex one. When talking about bone tissue, and bone structure, we have, in essence three main cell types which actually form it, while inside bones we have the appearance of other types of cells which are not directly related to the bone itself.

These three types of bone-related cells, are: the osteoblast, the osteocytes and the osteoclasts.

The osteoblast is essentially the basic cell unit of bone tissue and its orgin, like osteocytes, are the mesenchymal progenitor cells. The osteocyte, is another type of osteoblast but has the particular characteristic that it is start shaped, and it is immovable and trapped within the web created in a formed and calcified bone. They do not divide, they do not change, but remain during their period of life until they die. The third type is the osteoclast, the cell that is responsible for the reformation of bone tissue by breaking and reabsorbing bone tissue. An important fact about these cells is that through the process of reorption, they ensure the correct blood levels of calcium.