Conclusions
We conclude that irregularly shaped initial lymphatics may lead to efficient lymph formation induced by mechanical stimulation of the tissue.
Methods
To confirm stretch-induced expansion of initial lymphatics, a finite element model that simulated morphological changes on a computer and fluorescent image and immunohistochemical analyses in mouse skin were adopted. Next, to quantitatively analyze the stretch-induced expansion, a simulation study was performed using a viscoelastic model of the tissue including initial lymphatics.
Objective
The present study aimed to combine the physiological significance of irregularly shaped initial lymphatics and mechanisms of mechanical stimulation-induced lymph formation.
Results
On the finite element model, when the tissue was stretched, irregularly shaped lymphatics were confirmed to increase luminal volume compared with round-shaped lymphatics. Stretch-induced expansion of the real initial lymphatics was demonstrated by fluorescent images and histological studies. Thereafter, with the application of a viscoelastic model of the tissue, the relationship between the lymph formation rate (Q) and massage frequency (f) could be obtained using the following equation: <math><mrow><mi>Q</mi><mo>=</mo><mn>2</mn><mi>A</mi><mi>f</mi><mo>(</mo><mn>1</mn><mo>-</mo><msup><mi>e</mi><mrow><mo>-</mo><mn>1</mn><mo>/</mo><mn>2</mn><mi>τ</mi><mi>f</mi></mrow></msup><mo>)</mo></mrow></math> , where A and τ are constants. Excellent agreement was found between the previous data and the results of the present equation. Conclusions: We conclude that irregularly shaped initial lymphatics may lead to efficient lymph formation induced by mechanical stimulation of the tissue.