[Ultrastructure of the neural plexus of the wall of the anterior mesenteric artery in hens].

As it has been demonstrated in 10-day-old chickens by means of light and electron microscopy, the wall of the anterior mesenteric artery in hens has two well defined smooth muscle layers: longitudinal and circular. The innervation apparatus of this vessel wall consists of 3 plexuses (adventitial, muscular external and internal) which are parts of a single complex vascular plexus. All the neural fibres of this plexus are supposed to be adrenergic.