Development of innervation of coronary arteries in human foetus up until 230 mm. stage (mid-term).

Innervation of the coronary vessels is initiated before the 30 mm. stage of development. All the main branches of the coronary arteries are formed and in their definitive positions by the 40 mm. stage. Two plexuses have been shown for all the larger vessels after the 120 mm. stage. There are coarse-fibre and fine-fibre plexuses, situated at different levels in the tunica adventitia. Ganglion cells have been found in relation to the coronary arteries over the ventricles. This confirms the part played by the vagal system in the innervation of the ventricle. No nerve endings were seen in the tumica media.