Thymus

  • thymus
    illu thymus.jpg
    thymus
    details
    precursorthird pharyngeal arch
    systemlymphatic system, part of the immune system
    lymphtracheobronchial, parasternal
    functionsupport the development of functional t cells
    identifiers
    latinthymus
    d013950
    a13.1.02.001
    9607
    anatomical terminology
    [edit on wikidata]

    the thymus is a specialized primary lymphoid organ of the immune system. within the thymus, t cells mature. t cells are critical to the adaptive immune system, where the body adapts specifically to foreign invaders. the thymus is composed of two identical lobes and is located in the anterior superior mediastinum, in front of the heart and behind the sternum. each lobe of the thymus can be divided into a central medulla and a peripheral cortex which is surrounded by an outer capsule.

    the cortex and medulla play different roles in the development of t cells. cells in the thymus can be divided into thymic stromal cells and cells of hematopoietic origin (derived from bone marrow resident hematopoietic stem cells). developing t cells are referred to as thymocytes and are of hematopoietic origin. stromal cells include epithelial cells of the thymic cortex and medulla, and dendritic cells. the thymus provides an environment for development of t cells from precursor cells. the cells of the thymus provide for development of t cells that are functional and self-tolerant. therefore, one of the most important roles of the thymus is the induction of central tolerance.

    the thymus is largest and most active during the neonatal and pre-adolescent periods. by the early teens, the thymus begins to decrease in size and activity and the tissue of the thymus is gradually replaced by adipose tissue (fat). nevertheless, residual t lymphopoiesis continues throughout adult life.

  • structure
  • development
  • function
  • clinical significance
  • society and culture
  • history
  • other animals
  • additional images
  • references
  • external links

Thymus
Illu thymus.jpg
Thymus
Details
PrecursorThird pharyngeal arch
SystemLymphatic system, part of the immune system
Lymphtracheobronchial, parasternal
FunctionSupport the development of functional T cells
Identifiers
LatinThymus
D013950
A13.1.02.001
9607
Anatomical terminology

The thymus is a specialized primary lymphoid organ of the immune system. Within the thymus, T cells mature. T cells are critical to the adaptive immune system, where the body adapts specifically to foreign invaders. The thymus is composed of two identical lobes and is located in the anterior superior mediastinum, in front of the heart and behind the sternum. Each lobe of the thymus can be divided into a central medulla and a peripheral cortex which is surrounded by an outer capsule.

The cortex and medulla play different roles in the development of T cells. Cells in the thymus can be divided into thymic stromal cells and cells of hematopoietic origin (derived from bone marrow resident hematopoietic stem cells). Developing T cells are referred to as thymocytes and are of hematopoietic origin. Stromal cells include epithelial cells of the thymic cortex and medulla, and dendritic cells. The thymus provides an environment for development of T cells from precursor cells. The cells of the thymus provide for development of T cells that are functional and self-tolerant. Therefore, one of the most important roles of the thymus is the induction of central tolerance.

The thymus is largest and most active during the neonatal and pre-adolescent periods. By the early teens, the thymus begins to decrease in size and activity and the tissue of the thymus is gradually replaced by adipose tissue (fat). Nevertheless, residual T lymphopoiesis continues throughout adult life.