Microlymphatics and lymph flow.
Level 5 - mechanism / opinion, no new human data
Narrative physiological review synthesizing anatomical and mechanical models without original clinical data.
PubMed 2217560 · doi:10.1152/physrev.1990.70.4.987
What was done
This narrative physiological review synthesized existing anatomical, structural, and mechanical evidence regarding the structure of microlymphatics and the forces governing lymph flow across various mammalian organs and humans.
What was found
The abstract reports no numerical data. It describes the anatomical organization where initial microlymphatics are nonmuscular endothelialized tubes that absorb interstitial fluid via transient pressure gradients generated by extrinsic tissue stresses (e.g., arterial pulsations, muscle contractions, respiration). Microscopic endothelial valves and bileaflet valves prevent backflow into the interstitium during compression, guiding lymph into downstream contractile collecting lymphatics equipped with smooth muscle.
Why it matters
The paper clarifies the mechanical distinction between passive extrinsic fluid absorption in initial nonmuscular lymphatics and active intrinsic propulsion in collecting vessels.
Limits
As a narrative review, it presents no original empirical measurements or quantitative meta-analysis. The abstract explicitly notes that decisive in vivo experiments quantifying the individual contributions of specific extrinsic pump mechanisms to whole-organ lymph flow were lacking.
Cited by
- supports The lymphatic system relies on skeletal muscle contractions, such as calf muscle action during walking, to pump and drain fluid.