[Microstructural characteristics of lymphatic vessels in skin tissues of acupoints "Taichong" and "Yongquan" in the rat].

ABSTRACT

OBJECTIVE: To provide a new method for investigating the histological characteristics of acupoints by obser-ving the microstructure of the lymphatic vessels in the skin tissue of "Taichong" (LR3) and "Yongquan" (KI1) regions. METHODS: Six male SD rats were used in the present study. The skin tissue of LR3 and KI1 from the hind foot were taken following transcardial perfusion with 4% paraformaldehyde. The skin tissues were cut into sagittal sections with a freezing microtome and stained by fluorescent immunohistochemistry with lymphatic vessel endothelial hyaluronan receptor 1 (LYVE-1), calcitonin gene-related peptide (CGRP), and phalloidin for displaying the lymphatic vessels, nerve fibers, and blood vessels, separately. The samples were viewed and recorded using fluorescent microscope and laser scanning confocal microscope. RESULTS: In the skin tissue of LR3 and KI1 regions, the lymphatic vessels, nerve fibers, and blood vessels were labeled with LYVE-1, CGRP and phalloidin, respectively. The lymphatic capillaries were found to start from the enlarged blind end and distribute in the dermis and subcutaneous tissues with various forms, crisscrossing. Abundant blood capillaries at various thickness distributed around the lymphatic capillaries in a parallel or crossed pattern, intermingled with free nerve fibers. CONCLUSION: The lymphatic capillaries, blood capillaries and nerve fibers extensively distribute in the skin tissues of LR3 and KI1 regions in rats, suggesting an involvement of the immunomodulation in the effects of acupuncture in pathological conditions, despite being not limited to the acupoint regions in the distribution of lymphatic capillaries.