109. Megakaryocytes are the major source of
1. Erythrocytes
2. Monocytes
3. Macrophages
4. Platelets

Question:

Megakaryocytes are the major source of:

1. Erythrocytes

2. Monocytes

3. Macrophages

4. Platelets

Correct Answer:

4. Platelets

Explanation:

Megakaryocytes are large, specialized cells found in the bone marrow that are responsible for the production of platelets. Platelets (also known as thrombocytes) are crucial for blood clotting and wound healing. These cells have a distinct role in hemostasis by adhering to the site of a vascular injury, helping to form clots that stop bleeding.

Breakdown of each option:

1. Erythrocytes:
   Erythrocytes (red blood cells) are not produced by megakaryocytes. They are derived from erythroblasts, which undergo a series of transformations to become mature red blood cells in the bone marrow.

2. Monocytes:
   Monocytes, which are a type of white blood cell, are derived from myeloid progenitor cells in the bone marrow, not from megakaryocytes.

3. Macrophages:
   Macrophages are differentiated from monocytes once they exit the bloodstream and enter tissues. Like monocytes, they do not come from megakaryocytes.

4. Platelets:
   Platelets are the key product of megakaryocytes. These cells undergo a process called endomitosis, where they replicate their DNA but do not undergo cell division. This results in a large, multinucleated cell that sheds small fragments of its cytoplasm, which become the platelets.

Conclusion:

The primary function of megakaryocytes is to produce platelets, essential for blood clotting and wound repair. They play a vital role in maintaining hemostasis and preventing excessive blood loss.

Correct Answer: 4. Platelets