Abstract
An experimental model of communicating hydrocephalus was developed based on intrathecal injection of human recombinant transforming growth factor-β1 (hrTGF-β1) in the mouse. To clarify the mechanism of this hydrocephalus model, the ultrastructure of the leptomeninx in the process of ventricular dilation was examined in C57/BL6 mice injected intrathecally with 60 ng of hrTGF-β1. The leptomeninx was examined at various periods after injection by light and electron microscopy. Immunostaining for fibroblasts and macrophages was also performed. Leptomeninx within a week after injection showed that the thin cytoplasmic processes of leptomeningeal cells formed a laminated structure with a meshwork, which was almost the same as the controls. In the second week, many cells with a round nucleus appeared in the leptomeninx. Immunohistochemically, these cells were positive for anti-fibroblast antibody and negative for anti-Mac-1 and anti-macrophage BM-8 antibodies. Three weeks later, the laminated structure was disrupted and abundant deposition of collagen fibers was found in the intercellular space of the leptomeninx. Such inter-meningeal fibrosis would disturb cerebrospinal fluid flow in the mouse leptomeninx and cause slowly progressive ventricular dilation.
