GENERAL HISTOLOGY

BONE

DEVELOPING BONE

Question [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
During endochondral ossification, what is the first step?
A
cartilage starts to calcify and periosteal bone collar forms
B
the epiphyseal plates are ossified
C
primary ossification centers form in the diaphysis
D
hyaline cartilage develops and is a model
Explanation: 

Detailed explanation-1: -This process involves the replacement of hyaline cartilage with bone. It begins when mesoderm-derived mesenchymal cells differentiate into chondrocytes. Chondrocytes proliferate rapidly and secrete an extracellular matrix to form the cartilage model for bone.

Detailed explanation-2: -Endochondral ossification is the process of bone development from hyaline cartilage. All of the bones of the body, except for the flat bones of the skull, mandible, and clavicles, are formed through endochondral ossification. In long bones, chondrocytes form a template of the hyaline cartilage diaphysis.

Detailed explanation-3: -Endochondral ossification can be divided into five stages: commitment, compaction, proliferation, growth, and finally, chondrocyte death and the generation of new bone. Phases 1 and 2: commitment and compaction. First, the mesenchymal cells commit to becoming cartilage (Figure 1A).

Detailed explanation-4: -Endochondral ossification begins with characteristic changes in cartilage bone cells (hypertrophic cartilage) and the environment of the intercellular matrix (calcium laying), the formation which is called as primary spongiosa. Blood vessels and mesenchymal tissues then penetrate into this area from the perichondrium.

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