The stratigraphical organisation of the microvascular systems of the porcine vocal folds.

The cranial and caudal vocal folds (CraF, CauF) of the glottis of adult minipigs (11-27 months; n = 12) were examined after immunohistochemical application of polyclonal anti-von-Willebrand-Factor and anti-Smooth-Muscle-Actin in serial paraffin sections. This examination aimed at a stratigraphical analysis of microvessels; data were compared with findings in humans which had been reported in the literature. (1) The distribution of the microvessels was very heterogeneous in the CraF and in the CauF, but a common pattern existed in both. (2) Characteristic vascular zones and rows were detected; each of them displayed a specific distribution and density of blood capillaries, arterioles, venules, lymphatic capillaries, and lymphatic precollectors. (3) A striking feature was the presence of a subepithelial Avascular Band and of a focal Avascular Area within the lamina propria of the fold's crests. (4) The vascular zones, the rows, the Avascular Band, and the Avascular Area could be allocated to specific layers of the lamina propria: subepithelial, superficial, intermediate, deep layer. (5) The loose Avascular Area at the level of the superficial layer of the lamina propria (in both CraF and CauF) corresponded to Reinke's space in humans in terms of structure and location. (6) The direction/course of blood and lymphatic microvessels shared common features with that of the human vocal fold.