Osteocyte in the context of "Bones"

A bone is a rigid organ that constitutes part of the skeleton in most vertebrate animals. Bones protect the organs of the body, produce red and white blood cells, store minerals, help regulate acid-base homeostasis, provide structure and support for the body, and enable mobility and hearing. Bones come in a variety of shapes and sizes and have complex internal and external structures.

Bone tissue (also known as osseous tissue or bone in the uncountable) is a form of hard tissue, specialised connective tissue that is mineralized and has an intercellular honeycomb-like matrix, which helps to give the bone rigidity. Bone tissue is made up of different types of bone cells: osteoblasts and osteocytes (bone formation and mineralisation); osteoclasts (bone resorption); modified or flattened osteoblasts (lining cells that form a protective layer on the bone surface). The mineralised matrix of bone tissue has an organic component of mainly ossein, a form of collagen, and an inorganic component of bone mineral, made up of various salts. Bone tissue comprises cortical bone and cancellous bone, although bones may also contain other kinds of tissue including bone marrow, endosteum, periosteum, nerves, blood vessels, and cartilage.

In histology, a lacuna is a small space, containing an osteocyte in bone, or chondrocyte in cartilage.

Bone canaliculi are microscopic canals between the lacunae of ossified bone. The radiating processes of the osteocytes (called filopodia) project into these canals. These cytoplasmic processes are joined together by gap junctions. Osteocytes do not entirely fill up the canaliculi. The remaining space is known as the periosteocytic space, which is filled with periosteocytic fluid. This fluid contains substances too large to be transported through the gap junctions that connect the osteocytes.

In cartilage, the lacunae and hence, the chondrocytes, are isolated from each other. Materials picked up by osteocytes adjacent to blood vessels are distributed throughout the bone matrix via the canaliculi.