An electron microscope study of the corpora cardiaca and secretory neurons in the aphid, Myzus persicae (Sulz.)

The corpora cardiaca (CC) and associated nerves of the aphid, Myzus persicae , have been examined with the electron microscope and their ultrastructure described. The CC is composed of intrinsic secretory cells, glial or interstitial cells, and a complicated region of intertwined, granule-filled axons. Three types of neuroeffector junctions were observed in this latter region. Secretory granules, presumably from brain or CC neuroglandular cells, are also present in axons of nerves leaving the CC and going to various target organs such as the corpora allata, pericardial cells, and visceral and somatic muscles. Granule-containing axons are present in each of these tissues and show contacts with the cells which resemble synapses. It is suggested that in these instances, the secretory material acts as a local hormone. At two sites along the lateral nerve from the CC, glandular cells containing large (200–290 m μ ) granules were observed. These cells appear to send a process along the lateral nerve, but the site of release of the granules is not known.