Osteoblasts are specialized bone cells crucial for the formation of new bone matrix, aptly remembered by the phrase "blasts build." These cells actively produce and secrete collagen fibers, which are strong and flexible, akin to a rope, providing structural integrity to the bone. Additionally, osteoblasts release enzymes that bind to calcium ions (Ca²⁺), facilitating the formation of hydroxyapatite crystals. These crystals are essential for imparting hardness to the bone.

Osteoblasts originate from osteoprogenitor cells, which are stem cells located in the periosteum (the outer connective tissue layer of the bone) and the endosteum (the inner connective tissue lining). When new bone formation is required, these progenitor cells differentiate into osteoblasts, which then lay down the new bone matrix. Some osteoblasts will eventually become embedded in the matrix they create, transforming into mature osteocytes, which are essential for maintaining bone tissue.

In terms of bone growth, osteoblasts play a significant role in increasing the width of bones. They deposit new bone on the outer surface, leading to an increase in size. As the outer bone expands, other cells, including additional osteoblasts, reshape the inner structure to accommodate the new dimensions. This dynamic process ensures that bones grow not only longer but also wider, adapting to the body's needs.