ERNST, H.H.*; RICHARDSON, J.F.; SATTERLIE, R.A.: Morphological Changes in an Asymmetric Neuron of the Right Pleural Ganglion in the Sexually Mature Vs. Immature Pteropod Mollusk

One of the largest neuron somata of the right pleural ganglion of Clione limacina belongs to a cell that does not have a homologue in the left pleural ganglion. In the immature animal, the soma is around 50um in diameter and appears translucent with substage illumination. In the mature animal, the soma is around 80um in diameter and appears opaque. With illumination from above, the cell is white in color. Light and electron microscopical examination of both immature and mature “Pleural White Cells” indicate the presence of numerous, large dense-cored vesicles in the cytoplasm of the mature animals, but not in the immatures. In addition, several smaller pleural neurons appear light opaque in mature animals. The appearance of the white color in the smaller neurons, but not in the Pleural White Cell, is coincident with immunoreactivity of small neurons to an antibody to Aplysia egg-laying hormone. Similarly, immunoreactive somata, to an Aplysia sensorin antibody, which is believed to specifically label primary mechanosensory neurons, is found in the right, but not the left pleural ganglion of sexually mature animals. Again, only small neurons are labelled. Thus significant morphological changes, and presumed physiological changes, occur in the right plerual ganglion of Clione when it develops sexual maturity.