EXFOLIATION OF EPITHELIAL-CELLS FROM THE PALLIAL ORGANS OF THE SEA SCALLOP, PLACOPECTEN-MAGELLANICUS

During routine feeding experiments in the field we discovered that adult Placopecten magellanicus were releasing large numbers of particles from the mantle cavity. These particles ranged in size from 6 to 15 mu m with a prominent peak at approximate to 10 mu m making it possible to recognize them using an electronic particle counter/sizer. Tissue samples were collected from individuals that were known to have released particles and from scallops that apparently had not. Light and scanning electron microscopy (SEM) were used to identify these particles as ciliated and non-ciliated epithelial cells. The number of scallops exfoliating cells was related to increasing water temperatures and the maximum stage of gamete development. SEM photomicrographs showed that at least some areas of the gill were devoid of cilia including those that comprise the lateral, laterofrontal and frontal tracts of the filaments. Exfoliation of these ciliated cells has obvious implications for the animal's ability to capture and transport food particles.