Chapter 7, Problem 1Q

Summary Introduction

Introduction:

T lymphocyteor T-cell is (white blood cellsubtype) a form of lymphocyte whichdoes a central part in (cell-mediated) immunity. Due to the existence of T-cell receptor on the surface of cell these cells can be differentiated from other lymphocytes likenatural killer cells and B cells.

Answer to Problem 1Q

Correct answer:

The correct answer is option (c) bone marrow→thymus → lymph nodes.

Explanation of Solution

Explanation/justification for the correct answer:

Option (c) bone marrow → thymus → lymph nodes. The development of T-cells takes place in the bone marrow from theHematopoietic Stem Cells but commonly their differentiation happens in the thymus. These cells enter the cortexregion of thymus and they migrate to thymic medulla for further differentiation. Mature T-cells (at the thymic medulla) are then liberated into the peripheral circulation. So, the correct answer is option (c).

Explanation for incorrect answer:

Option (a) Thymus → bone marrow → spleen. Development of T-cells takes place from bone marrow region to thymus and is completed in lymph nodes and no spleen is involved. So, this is an incorrect option.

Option (b) Thymus → bone marrow → thymus. The bone marrow is the initial tissue in which the developmental pathway of T cells begins. So, this is an incorrect answer.

Option (d) Lymph nodes → thymus → spleen. Lymph nodes is the final stage in the developmental pathway of T cells. So, this is an incorrect answer.

Option (e) Bone marrow → lymph nodes → thymus. The option shows the starting point of pathway of T-cells development. So, this is an incorrect answer.

Conclusion

Hence, in the bone marrow T-cells initiate and in thymus these mature and differentiate into different subtypes. The correct answer is option (c) bone marrow → thymus → lymph nodes.