Kondroblasti

Kondroblasti (chondroblasts) are cartilage-forming cells that play a central role in cartilage development and growth. They originate from mesenchymal stem cells and reside mainly in the perichondrium or in the early cartilage template. During embryogenesis, mesenchymal cells condense and differentiate into chondroblasts, which synthesize and secrete the extracellular matrix of cartilage, rich in collagen type II and proteoglycans such as aggrecan. As they accumulate matrix, chondroblasts become embedded in lacunae and mature into chondrocytes, the cells that maintain mature cartilage.

Chondroblasts are essential for both appositional growth (growth in thickness) and, in long bones, for the cartilage template that undergoes endochondral ossification to form bone. The matrix they generate provides the structural and biochemical environment for chondrocyte function. Cartilage is avascular, so nutrients diffuse from surrounding tissues, a factor that influences chondroblast activity and matrix composition.

Key regulatory pathways in chondrogenesis include Sox9 signaling, which promotes chondrogenic differentiation, and growth plate regulators such as Indian hedgehog (Ihh) and parathyroid hormone-related peptide (PTHrP), which coordinate proliferation and hypertrophy of chondrocytes. Chondroblasts persist in the perichondrium of maintaining cartilage and contribute to repair processes, and can be the origin of chondroblastoma, a rare cartilage-originating tumor.