Electron microscopic investigation of sulcus vocalis

This investigation was carried out to determine the histopathologic findings of sulcus vocalis in two human adult larynges. Observations were made by light and transmission electron microscopy. The results are summarized as follows. Sulcus was confined to the squamous epithelium area. The basement membrane thickness increased at the sulcus. The sulcus was situated in the superficial layer of the lamina propria, which was thin around the bottom of the sulcus. Collagenous fibers were dense, and fibrous long-spacing collagen was seen around the bottom of the sulcus. Elastic fibers decreased in number and were composed predominantly of microfibrils and reticular amorphous substances. In the maculae flavae, the fibroblasts were decreased in number and degenerated. Collagenous and elastic fibers, synthesized by fibroblasts in the maculae flavae, were decreased. There were many abnormal elastic fibers in the maculae flavae. The quality and quantity of the fibrous components were changed in the mucosa of sulcus vocalis, owing in part to dysfunction of the fibroblasts and abnormal fibrogenesis in the maculae flavae.