The flow path of alcian blue from the acupoint BL23 to the surface of abdominal organs.

Two hours after Alcian Blue (AB) dye was injected at the rat acupoint BL23, the abdominal cavity was examined and AB-stained threadlike structures were observed on the right abdominal cavity. Those threadlike structures were mainly distributed on the surfaces of the duodenum, colon and cecum. These threadlike structures were thin (about 50 microm) and moved freely, and were connected to corpuscles that were about 500 x 200 microm wide and also stained with AB. On analyzing the histology of the threadlike structures, rod-shaped nuclei, bundles of collagen fibers, reticulofibers, and squamous-like epithelial cells were observed. Immune cells and some sinuses were inside the threadlike structures. These characteristics describe those of Bonghan ducts. The flow paths from the acupoint to internal organs can possibly be used as paths for drug delivery.