PERIOSTEUM E ENDOSTEUM
As mentioned at the beginning of this chapter, with rare exceptions, all bone surfaces are lined by cells. These cells can be of three types: osteoprogenitor cells (bone tissue stem cells), osteoblasts, or osteoclasts.
Osteoblasts constitute the majority of the cells lining the inner bone surface of a long bone, and form a layer called endosteum (highlighted in light blue). The endosteum is generally thin, often formed by one layer of cells arranged over the bone matrix.
Observe in the next page that the endosteum lines not only the large bone cavities (e.g., the medullary canal), but also all small cavities present between the trabeculae of the cancellous bone and even the inner wall of the Haversian canals.
The periosteum is highlighted in pink.
Osteocytes are highlighted in green.
Osteoblasts constitute the majority of the cells lining the inner bone surface of a long bone, and form a layer called endosteum (highlighted in light blue). The endosteum is generally thin, often formed by one layer of cells arranged over the bone matrix.
Observe in the next page that the endosteum lines not only the large bone cavities (e.g., the medullary canal), but also all small cavities present between the trabeculae of the cancellous bone and even the inner wall of the Haversian canals.
The periosteum is highlighted in pink.
Osteocytes are highlighted in green.
Periosteum and endosteum. Staining: HE. Small magnification.
