Chondroide

Chondroide is a term used in anatomy and embryology to refer to cartilage-like tissue or to a cartilage-forming precursor in the development of the vertebrate skeleton. The word derives from chondro-, cartilage, and -idae or -eide, meaning resembling; in older literature it is sometimes used interchangeably with cartilage anlagen or cartilaginous primordium.

Chondroide tissue consists mainly of mesenchymal cells that differentiate into chondroblasts and chondrocytes, embedded in an extracellular matrix rich in proteoglycans and type II collagen. In early stages it is typically avascular and relies on diffusion for nutrient supply; the matrix is relatively rich in water and provides a semi-rigid scaffold.

During development, chondroide gives rise to cartilage through chondrogenesis. In endochondral ossification, the chondroide model first forms a cartilaginous template that is progressively replaced by bone tissue, while some regions persist as cartilage in the mature skeleton (e.g., articular surfaces and the growth plates).

In modern English-language anatomy, the term chondroide is uncommon and largely historical; contemporary texts prefer cartilage, chondrogenic tissue, or the terms cartilage anlage and cartilaginous primordia to describe these structures. The usage persists in some non-English sources and in comparative anatomy and palaeontology contexts.

See also: cartilage, chondroblast, chondrocyte, chondrogenesis, endochondral ossification.