Ruffed cell: a new type of neuron with a distinctive initial unmyelinated portion of the axon in the olfactory bulb of the goldfish (Carassius auratus). III. Three-dimensional structure of the ruffed cell dendrite.

The three-dimensional structure of the ruffed cell dendrite in the olfactory bulb of the goldfish (Carassius auratus) was studied by means of light and high-voltage electron microscopy of Golgi-impregnated material, combined Golgi-electron microscopy, and electron microscopy of serial thin sections. Ruffed cell dendrites ramify in the glomerular area with tufted branching patterns. They give rise to many appendages of various shapes and sizes: sheetlike processes, fingerlike projections, or small tuftlike appendages. These appendages, singly or together, appear to entwine or cover other neuronal processes. In thin sections ruffed cell dendritic appendages frequently look like glial processes; that is, they appear to conform in shape to the contours of surrounding neuronal elements, such as mitral and granule cell dendrites. Ruffed cell dendrites display intimate relationships with mitral cell dendrites. The former appear to coil around and cover the latter. Nothwithstanding the intimate relationship between ruffed cell dendrites and mitral cell dendrites, there seem to be no synaptic connection between them. Ruffed cell dendrites bear a rather small number of presynaptic and postsynaptic sites, most of which area with granule cell dendrites. Ruffed cell dendrites seem to receive no synapses from olfactory nerve terminals.