In humans, stem cells from which all blood cell types are developed are found in the:

• A. Peripheral circulation.
• B. Bone marrow.
• C. Lymphatic vessels.
• D. Lymph nodes.

Answer: (B)

Verified step by step guidance

1. Understand the role of stem cells in the human body: Stem cells are undifferentiated cells that have the potential to develop into different cell types. In the context of blood cell formation, these are known as hematopoietic stem cells.
2. Identify the primary location of hematopoietic stem cells: In humans, hematopoietic stem cells are primarily located in the bone marrow, which is the soft tissue found in the hollow interior of bones.
3. Differentiate between the options provided: Peripheral circulation, lymphatic vessels, and lymph nodes are not primary sites for the development of blood cells. They play different roles in the circulatory and immune systems.
4. Recognize the function of bone marrow: Bone marrow is the key site for the production of all blood cell types, including red blood cells, white blood cells, and platelets, through a process called hematopoiesis.
5. Conclude that the bone marrow is the correct answer: Based on the understanding of hematopoietic stem cells and their primary location, the bone marrow is where all blood cell types are developed in humans.