VBDI 4997E Pre-veterinary/medical Histology Module 6: Lymphatic System

Flashcards covering essential terms and definitions related to the lymphatic system as outlined in Module 6 of the Pre-veterinary/medical Histology course.

Lymph

A pale liquid generated in tissue spaces, similar in composition to plasma and containing white blood cells.

Lymphatics

Special vessels through which lymph flows.

Thoracic duct

The largest lymphatic vessel that drains lymph into the cranial vena cava.

Primary lymphoid organs

Organs like the thymus and bone marrow where lymphocytes originate.

Thymus

A primary lymphoid organ where T lymphocytes mature, consisting of lobules with a cortex and medulla.

Cortex (of the thymus)

The area of the thymus containing mature T lymphocytes.

Medulla (of the thymus)

The area of the thymus containing immature T lymphocytes, appearing paler than the cortex.

Stromal cells

Cells that form the framework of lymphoid organs, providing structure.

Hassal’s corpuscles

Whorled structures formed by epithelial reticular cells in the medulla of the thymus.

Secondary lymphoid organs

Lymphoid organs, such as lymph nodes and spleen, involved in the activation of lymphocytes.

Lymph node

A nodular structure consisting of a cortex filled with follicles and a medulla.

Follicles (in lymph nodes)

Round structures in the cortex of lymph nodes, containing B lymphocytes.

Germinal center

The inner core of follicles in lymph nodes, made up of immature B lymphocytes.

Para-follicular zone

Non-follicular regions of the lymph node cortex where T cells are located.

Spleen

An organ known as the 'graveyard of red blood cells,' without a cortex or medulla.

Periarteriolar lymphatic sheaths (PALS)

Capsules of T lymphocytes surrounding splenic blood vessels.

White pulp

Regions in the spleen where lymphocytes are present.

Red pulp

Regions in the spleen consisting of sinuses filled with red blood cells.

Macrophages

Cells in the spleen that digest recycled red blood cells and iron.