Question

Endosteum is composed of
A. White fibrous connective tissue
B. Reticular connective tissue
C. Yellow fibrous connective tissue
D. Areolar connective tissue

Answer 1

Endosteum is a thin vascular membrane made up of connective tissue. It lines the inner surface of the bony tissue that forms the medullary cavity of long bones. It is composed of fat cells and mesenchymal stem cells. It aids in growth of the bone, repair and remodeling.

Complete answer:
The endosteum is a thin vascular membrane made up of connective tissues. It lines the inner surface of the bony tissue that forms the medullary cavity of long bones. It is composed of Reticular connective tissue. Endosteum is a very thin looking bony structure. Fibroblasts are abundantly present in the endosteum.
When a person is malnutritioned for longer periods, the endosteum gets resorbed.
Endosteum is of three types based on its site:

Osteon endosteum- lines the nerves and blood vessels (osteon).
Cortical endosteum- lines the bone marrow cavity.
Trabecular endosteum- lines the trabecula near the developing part of bone.

However, the correct answer to this question is option ‘B’-reticular connective tissue.

Additional Information:
The name reticular connective tissue is given to it due to the presence of reticular fibers. These fibers make up the tissue and these reticular fibers are made up of fibroblasts. They have high cellular content and form a mesh like pattern. These tissues are found in the kidney, spleen, lymph nodes, and bone marrow. Their function is to provide structural support.

Note: The opposite of endosteum is periosteum. It lies on the outer surface of the bone. It is thick in initial years of life and the thickness decreases as age advances. It consists of two layers- outer fibrous membrane and inner cellular layer.