Evidence for novel tubular-bundle structures entangled in the fascia of the inner abdominal wall of a rat

Abstract

After incubation with Janus Green B in the peritoneal cavities of rats, lymph-vessel-like structures (LSs) were noticed under a stereomicroscope to run parallel to each other with rectangular branches on the inner abdominal wall; rarely were these LSs seen to connect with peritoneal LSs. These LSs were identified by using fluorescence microscopy (FM) at a magnification of 1,000X and confocal laser scanning microscopy (CLSM) to be lymph-vessel-like bundle structures (LBSs). Serial cross-sections of these LBSs were microscopically examined by using hematoxylin and eosin staining, Mattson trichrome staining, terminal deoxynucleotidyl transferase dUTP nick end labeling, and immunohistochemistry (IHC) with Lyve 1 and CD 31. The histology data from these LBSs revealed such novel characteristics as parallel clusters of live cells wrapped by collagen fibers of the fascia and an IHC different from those of lymphatic and blood vessels, being the novel bundle structures (NBSs). Under FM and CLSM with optical sections, some of the NBSs were observed to be able to swell like tiny balloons, implying that the bundle structures were hollow. Moreover, transmission electron microscopy images of two different cross-sections of an NBS showed it to be composed of four parallel tubules involving three kinds of sinuses with neither axons nor Schwann cells in the outermost wall, thus being a novel tubular-bundle structure (NTBS). The results of this research make evident with high repeatability (10/11) that beyond the orthodoxy of a single-tube system of blood and lymph vessels, a system of NTBSs is widely entangled in the fascia of the inner abdominal wall of a rat. Thus, the author suggests that NTBS-related functions and the entire NTBS network should be explored.

Keywords: B; Bonghan duct (primo vessel); Confocal laser scanning microscopy; Fascia; Fluorescence microscopy; Janus Green; Transmission electron microscopy.