Vascularization of the brain in guinea pig. IV. Angioarchitectonics of the tectum, tegmentum, and crura mescencephali.

Out of three parts of the midbrain the richest vascularization is observed in the tegmentum in which are localized many nuclei. Particularly abundant blood supply shows the main nucleus of the oculomotor nerve. Less vascularized is the central oculomotor nucleus, and scanty blood vessels are found within the autonomic nucleus of the oculomotor nerve. Dense vascular net is found in the supratrochlear nucleus which lies in the central gray substance of the midbrain. Also, dense vascular net is noted within the red nucleus, trochlear nucleus, and the dorsal raphe nucleus. Within the substantia nigra less vascularized is its compact part. Very weak vascularization is observed in the periaqueductal gray and in the crura cerebri. Within the tectum more blood vessels are found in the inferior colliculus as compared with the superior colliculus. Within the crura cerebri the blood vessels do not form vascular net and they ascend into tectum and tegmentum.