The lymphatic system in vertebrates is a network of conduits that carry a clear fluid called lymph. It also includes the lymphoid tissue through which the lymph travels. Lymphoid tissue is found in many organs, particularly the lymph nodes, and in the lymphoid follicles associated with the digestive system such as the tonsils. The system also includes all the structures dedicated to the circulation and production of lymphocytes, which includes the spleen, thymus, bone marrow and the lymphoid tissue associated with the digestive system[WP]. [ ]

This is just here as a test because I lose it

Term information

database cross reference

uberon_slim, vertebrate_core

depicted by

external definition

Part of the circulatory system which consists of a series of vessels which collect blood (exclusive of erythrocytes) which seep through capillary walls and return it to the veins.[AAO]

external ontology notes

We follow FMA and MA in distinguishing between lymphatic system and lymphoid system, with lymhoid tissue part of the non-lymphatic component, although these terms are often used interchangeably. We assume the ZFA term lymphatic tissue actually corresponds to the broader class (e.g. ZFA lymph node in the ZFA lymphatic system). See tracker for more comments.

has alternative id


has narrow synonym

lymphatic system

has related synonym

lymphatic circulatory system
lymphatic drainage system
systema lymphoideum

homology notes

Tetrapods have evolved distinct lymphatic systems, in which lymphatic capillaries help drain most of the tissues of the body.[well established][VHOG]



taxon notes

The lymphatic systems of reptiles and some birds have lymph hearts, and both groups have extensive lymph vessels, but their functional role in both lymph movement and plasma volume homeostasis is almost completely unknown [10.1152/japplphysiol.00201.2013]
The lymphatic system of anuran amphibians is characterized by large lymphatic sacs and two pairs of lymph hearts that return lymph into the venous circulation but no lymph vessels per se [10.1152/japplphysiol.00201.2013]