The osteocytes are the mature bone cells responsible for maintaining the bone matrix. They originate from osteoblasts, which are the cells that build new bone. When osteoblasts become embedded in the matrix they create, they transform into osteocytes, which can be thought of as "trapped" osteoblasts. These osteocytes reside in small chambers called lacunae (plural: lacunae), which provide them a space to live while still being functional.

One of the primary roles of osteocytes is to monitor bone stress. Bones are constantly undergoing a process of remodeling, where old bone is removed and new bone is formed. Osteocytes detect stress in the bone and send signals to initiate this remodeling process. When they sense that a particular area of bone is under stress, they communicate with osteoclasts to remove the damaged bone, allowing osteoblasts to come in and build new bone. This cycle ensures that the bone remains healthy and strong.

In addition to their role in monitoring stress, osteocytes also contribute to calcium homeostasis. Bones store a significant amount of calcium, which is essential for various bodily functions. Osteocytes help regulate the release and storage of calcium in the bones, working alongside osteoclasts and osteoblasts to maintain appropriate calcium levels in the blood and other tissues.

Despite being embedded in the bone matrix, osteocytes are not completely isolated. They have small projections that extend into tiny channels called canaliculi, allowing them to communicate with neighboring cells and exchange nutrients and waste products. This communication occurs through structures known as gap junctions, which facilitate the diffusion of materials between cells. This interconnected network ensures that osteocytes can receive the necessary nutrients and remove waste, maintaining their health and functionality.

To summarize, osteocytes play a crucial role in bone health by monitoring stress, contributing to calcium homeostasis, and maintaining communication with other cells. They originate from osteoprogenitor cells, develop into osteoblasts, and eventually become osteocytes, where they can live for many years, sometimes even decades, until they are replaced during the bone remodeling process.