Meeting Abstract
There appear to be a limited number of ways that image-forming eyes can be designed, but it is not clear how many ways the processing centers that are associated with them can be formed. Scallops (Family Pectinidae) are bivalve mollusks with dozens of eyes along the edges of their valves. Although the anatomy of their eyes has been studied, little is known about the processing centers that accompany them. It is known that the optic nerves of these eyes project to the dorso-lateral lobes (DLL) of the parieto-visceral ganglion (PVG), a nerve center that is situated on the adductor muscle and separate from the cephalic ganglion. Further, the optic nerves appear to maintain a somatotopic arrangement as they project to globular neuropil in the DLL termed glomeruli. These glomeruli exist in relatively equal number to the eyes and are spaced along the length of the DLL. This system may be an example of visual processing that has evolved separately from the cephalic visual processing centers found in other bilaterians. Furthermore, it is not known if or how scallops integrate images collected separately by their dozens of eyes. Here, we use immunohistochemistry and confocal imaging to study the structure of the DLL and glomeruli in bay (Argopecten irradians) and sea (Placopecten magellanicus) scallops. In addition, we investigate the morphology of single neurons within the glomeruli using Golgi-Cox silver impregnation. The glomeruli of scallops are then compared to the mushroom bodies of other sighted invertebrates via the comparison of individual cell morphologies and the organization of neuropil. Through this comparison, we will evaluate whether these separately evolved structures may serve a similar purpose to the mushroom bodies of other invertebrates.
