Mucosal microvasculature of the gastric pars nonglandularis and margo plicatus in the horse: A scanning electron microscopic study on corrosion casts

Abstract

The microvascularisation of the equine non-glandular gastric mucosa was investigated using corrosion casts for scanning electron microscopy. Specimens from 11 healthy horses were examined. Corresponding to the high incidence of gastric lesions in the margo plicatus, special attention was paid to the differentiation between the pars nonglandularis and the margo plicatus as a distinct area of the aglandular mucosa. In both areas, the blood vessels of the lamina propria mucosae were arranged in three vascular layers; i.e. I) a basal, II) an intermediate, and III) a subepithelial horizontal level. In the basal (I) and in the intermediate (II) layers the vascular supply was organised in arterial retia - rete arteriosum profundum, rete arteriosum subpapillare - and venous plexus - plexus venosus profundus, plexus venosus subpapillare. Vertical interconnections integrated the layers into the vascular network of the entire lamina propria. The subepithelial (III) layer represented the blood vessels of all the individual connective tissue papillae in the lamina propria mucosae. Ansae capillares intrapapillares were found in the pars nonglandularis. In contrast, each of the papilla of the margo plicatus contained a "cone shaped" rete capillare intrapapillare. The thicker epithelium and lamina propria mucosae of the margo plicatus was therefore supplied by less numerous, but longer intrapapillary blood vessel systems. The typical vascular components of the margo plicatus may be considered to be one of several links in the etiological chain which characterises gastric mucosal lesions in the horse's stomach.