Geometrical differences among homologous neurons in mammals.

The dendritic arbors of sympathetic neurons in different species of mammals vary systematically: the superior cervical ganglion cells of smaller mammals have fewer and less extensive dendrites than the homologous neurons in larger animals. This difference in dendritic complexity according to body size is reflected in the convergence of ganglionic innervation; the ganglion cells of progressively larger mammals are innervated by progressively more axons. These relations have implications both for the function of homologous neural systems in animals of different sizes and for the regulation of neuronal geometry during development.