thymocyte

blood cell

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Last updated

July 16, 2026

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A thymocyte is a type of white blood cell, specifically a lymphocyte, that matures in the thymus. These cells are crucial for the immune system, as they develop into T cells, which are responsible for identifying and fighting off foreign substances like viruses and bacteria.1

The thymus, a lymphoid organ located beneath the breastbone, plays a vital role in T cell maturation. It grows rapidly after birth and then begins to shrink after puberty. Within the thymus, lymphocytes proliferate and differentiate into various types of T cells, including helper T cells, regulatory T cells, and cytotoxic T cells. These mature T cells then circulate in the blood and lymphatic system to protect the body from disease.21

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lymphatic system
Thymus
…thymus, developing T cells, called thymocytes, come to distinguish between the body’s own components, referred to as “self,” and those substances foreign to the body, called “nonself.” This occurs when the thymocytes undergo a process called positive selection, in which they are exposed to self molecules that belong to the…
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…thymus, developing T cells, called thymocytes, come to distinguish between the body’s own components, referred to as “self,” and those substances foreign to the body, called “nonself.” This occurs when the thymocytes undergo a process called positive selection, in which they are exposed to self molecules that belong to the…
Read More