What are the two main processes of bone formation?

Bones develop through two key processes: membranous ossification (directly from mesenchyme) and cartilaginous (endochondral) ossification (from a preformed cartilage model).

How does cartilage form during development?

Cartilage forms when mesenchymal cells condense and differentiate into chondroblasts, which secrete matrix. Some become enclosed as chondrocytes within this matrix.

What are the different types of cartilage and their characteristics?

Cartilage is classified into three types based on matrix composition: Hyaline cartilage is homogeneous and glassy with fine collagen fibers. Fibrocartilage is dense and white with visible collagen fibers. Elastic cartilage is yellowish and flexible due to elastic fibers.

What is the role of the perichondrium in cartilage?

The perichondrium is a fibrous covering formed from mesenchymal cells that surrounds cartilage, providing nourishment and support for its growth.

Which bones are formed by membranous ossification?

Membranous ossification forms flat bones, such as those in the cranial vault and face.

Which bones are formed by cartilaginous ossification?

Cartilaginous ossification forms long bones (like those in the limbs) and the base of the skull.

What are some clinical conditions related to bone formation defects?

Defects in ossification can lead to conditions like cleidocranial dysostosis, which affects membranous ossification and causes absent clavicles and delayed cranial ossification, and achondroplasia, which affects endochondral ossification and leads to dwarfism with short limbs.

Bone & Cartilage Development – Ossification Types

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