Direct innervation of the Drosophila melanogaster larval aorta

The heart rate of larval Drosophila is modulated by various biogenic amines and peptides. The actions have always been assumed to be due to direct action on the heart since the larval heart was not known to be innervated. A recent study showed a difference in the sensitivity of the larval heart to serotonin when the CNS was ablated, thus suggesting a direct neural input. Here, we show that GFP tagged motor neurons and nerve terminals are present on the aortic region of the heart. Motor neuron cell bodies also exist outside the CNS. Transmission electron microscopy reveals the direct innervation in the aortic tissue. Thus, developmental and regulatory questions in this genetic model can now be addressed in relation to heart development and neural control.