Anatomy · MU Sofia

Cardiovascular system · 135. Thymus.

Covers the thymus as a primary lymphoid organ where T lymphocytes mature, including its position in the superior mediastinum behind the sternum and how it changes from the neonatal period through to old age. Describes the structure, moving from the capsule and trabeculae to the lobes, cortex, medulla and corticomedullary junction, with Hassall's corpuscles and its vessels. Ends with its functions: T-cell maturation and positive and negative selection, the latter section left unfinished.

Inside: 3 sections · 2 labelled pictures · 13 flashcards · 1 min

Topic 123 of 264 in the MU Sofia syllabus for Anatomy (Dental Medicine, Year 2). The free AceMed note covers it in 3 sections, about 162 words (1 min of reading), with 13 flashcards.

In this note

  1. THYMUS
  2. Structure:
  3. Functions:

THYMUS

  • It is primary lymphatic organ (Produce T & B lymphocytes)
  • Location: ventral part of the superior mediastinum, just behind the Sternum.
  • It contains T-lymphocytes undergoing maturation.
  • The thymus is the largest and most active during the neonatal (newborn) period

During the teenage years it begins to atrophy & involute.

After the age of around fifty, the thymus is almost completely replaced by an adipose tissue

Structure:

  1. 1. Capsule - connective tissue.
  2. 2. Trabeculae - Extensions from the capsule.
  3. 3. Thymic Lobes: right & Left lobes
  4. 4. Cortex: Contains immature T-cells (thymocytes) that undergo maturation & selection processes.
  5. 5. Medulla: Contains mature T cells that have successfully passed through the processes.
  6. 6. Criticomedullary junction: the transition zone between the cortex & medulla.
  1. 7. Thymic (Hassal's) Corpuscles: structures found in the medulla.
  • Their exact function is not fully understood.
  1. 8. Thymic Arteries & veins.

Functions:

  1. 1. Facilitate the maturation of T-cells
  2. 2. Positive & Negative Selections
  • ↳ to detect which T-cells can be send to ..

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