The vascular architecture of the vestibule and the endolymphatic duct and sac of the rat

Abstract

The blood vessels of the vestibule and the endolymphatic duct and sac (ES) of the rat were reproduced with methacrylate casting medium and observed under a scanning electron microscope. Results were as follows.1. The veins from the vestibule emptied into the vein of the vestibular aqueduct (VVAQ).2. Some veins of the utricle drained into the saccular vein.This findings means that the saccular vein and the vein of the superior-lateral semicircular canal (VSLSC) might be a collateral venous drainage with each other.3. The hook of the cochlea had two venous drainage system.One of them drained into the vein of the vestibular aqueduct, and the other drained into the vein of the cochlear aqueduct. This fact supported the presence of the collateral route between the cochlear vessels and the vestibular vessels.4. In the human, the vein of the vestibular aqueduct ran through the paravestibular canaliculus, but in the rat it ran through the vestibular aqueduct, and a small vessel ran along the VVAQ between the vestibule and the ES.5. The plexus of the vessels of the ES was triangular in shape, and had anastomoses with the vessels of the surrounding bone and dura, and drained into the VVAQ at one to four points.6. Intermediate portion of the plexus were sinusoid like capillaries. This structure was suitable for the function of the ES or the resorption of endolymph.7. Two branches of the posterior meningeal artery which derived from the occipital artery entered the ES along both sides of the sigmoid sinus (SS). In some cases, they gave off numerous twigs to the plexus of the ES from the distal portion and in other cases one of them ran laterally to the SS, coursed along the rim of the ES and ramified numerous twigs to the ES.8. Rat is suitable for the experimental animal to study vascular lesions of the human inner ear.