For tracking the primo vascular system, we observed the primo vessels in vivo in situ using the lipopolysaccharide (LPS) response in the lymphatic vessels of a rabbit. Injection of LPS (200 μg/kg) into the lymph nodes resulted in greatly stained primo vessels, which were swollen in some cases. We were able to obtain comparative images through alcian blue and diaminobenzidine staining, which clearly showed different morphologies of the primo vessels. The mechanism causing the response of the primo vessels to the injected LPS is still unclear; however, these results might be a first attempt at giving an explanation of the function of the primo vascular system and identifying the changes in the structure and function of the primo vascular system in response to an external stimulus such as an injection of LPS.

The effects of stimulation with sound and ultrasonic waves of a specific bandwidth on the microdissection of primo vessels in lymphatic vessels of rabbit were investigated. The primo vessels stained with alcian-blue dye injected in the lymph nodes were definitely visualized and more easily isolated by sound-wave vibration and ultrasonic stimulation applied to rabbits at various frequencies and intensities. With sound wave at 7 Hz and ultrasonic waves at 2 MHz, the probability of detecting the primo vessels was improved to 90%; however, without wave stimulation the probability of discovering primo vessels was about 50% only. Sound and ultrasonic waves at specific frequency bands should be effective for microdissection of the primo vessels in the abdominal lymph of rabbit. We suggest that oscillation of the primo vessels by sound and ultrasonic waves may be useful to visualize specific primo structure, and wave vibration can be a very supportive process for observation and isolation of the primo vessels of rabbits.