lymphatic vs lymphoid system

[cmungall]

Both MA and FMA distinguish between lymphatic and lymphoid systems (FMA explicitly has a class "non-lymphatic lymphoid system", which MA does not). Neither have definitions. Definitions or at least disambiguating systems would be useful here, as the majority of sources use these terms loosely and interchangeably (Britanica even includes bone marrow as part of the lymphatic system!)

A reasonable assumption is that the lymphatic system is the cardiovascular component of the lymphoid system, including the lymphatic vessels but excluding lymphoid tissue such as tonsils. MA and FMA are consistent here -- more or less; let's ignore the weird FMA "set of X" terms and the fact that the FMA class lymphoid tissue isn't considered part of any system.

However, MA includes lymph node in lymphatic system, whereas FMA has lymph node as outside of the lymphatic system, but in the lymphoid system. In FMA it is part of the lymphatic system, but MA and FMA could be considered consistent here as the FMA relationships are: LN constitutional part of lymphatic tree organ system part of lymphatic system. "constitutional" part could be considered broader than the part_of used by MA, RO and all other AOs (but I'm no expert on the FMA relations).

(ZFA include lymph node in lymphatic system, but they don't introduce any lymphatic/lymhoid distinction, their term could be considered equivalent to the broader term and of course things get murkier as we move outside mammalia anyway)

This isn't an actual request for any change in the MA - just a confirmation that the current structure is intentional. In the absence of definitions, a disambiguating synonym might be a good idea (e.g. one can imagine a user coming to MGD doing an AO search, clicking "lymphatic system" when really they were interested in the "lymphoid system")

Original comment by: cmungall

Original Ticket: obo/mouse-anatomy-requests/37

[cmungall]

• assigned_to: nobody --> hayamizu

Original comment by: tfhayamizu

[cmungall]

Re: "MA includes lymph node in lymphatic system"

In the MA, lymph node is part of lymphoid system and vascular system

Re: "FMA has lymph node as outside of the lymphatic system, but in the lymphoid system. In FMA it is part of the lymphatic system"

My understanding is that, in the FMA, “lymph node is an “organ component of the lymphatic tree organ, which has subclasses "right lymphatic duct tree" and "thoracic duct tree." “Lymph node group” is “set of organ components” that is part of the “lymphatic tree organ”

The vascular tree as an organ concept is somewhat of a confusing one, and it is not clear precisely what constitutes a "lymphatic tree organ" of which "lymph node group" is a part. However, it seems to me that lymph nodes may be part of the "tree organ" without being part of the "lymphatic system," which is comprised of vessels.

Original comment by: tfhayamizu

[cmungall]

lymphatic vs. lymphoid system notes

Original comment by: tfhayamizu

[cmungall]

Correction to previous note:
In the MA, lymph node is part of lymphoid system, NOT vascular NOR lymphatic system.

It is clear that "lymphatic system" and "lymphoid system" are defined and used inconsistently. The lymphatic system is comprised of lymphatic (lymph conducting) vessels, but may or may not include lymph nodes. Some descriptions also include other lymphoid tissues, which really does not seem appropriate. The lymphoid system would be expected to consist of all lymphoid tissues (containing and/or producing lymphocytes) but, depending upon the reference source, may or may not include lymphatic vessels.

For now, we will retain the current hierarchical structure shared by the MA and FMA, ignoring the complexities imposed by the FMA concept "lymphatic tree organ" which the MA does not currently include. Furthermore, I agree that disambiguating synonyms and definitions should be provided and will try to come up with appropriate ones.

Original comment by: tfhayamizu

[cmungall]

• labels: --> other request
• status: open --> closed-accepted

Original comment by: tfhayamizu