Morphology and behavior of isolated living cells from Bugula neritina larvae (Bryozoa: Cheilostomata)

Living cells were dissociated from coronate larvae of Bugula neritina using the enzyme papain to study their morphology and behavior. Isolated cells were described from video recordings using an inverted microscope equipped with normal and high-speed cameras, and squashes of intact and papain-treated larvae were carefully examined to further identify the origin of isolated cells. The effects of papain were reproducible and cell group liberation was predictable with time. Dissociation proceeded in two distinct phases, and isolated cells were grouped into surface ciliated cells and interior cells. Eight types of surface ciliated cells were identified: coronal cells, plume cells, three previously undescribed cells from the pyriform groove (mohican cells, sweepers 1 and 2), fright cells from between the pyriform organ and the apical organ, and apical and oral ciliated cells. Because of vigorous ciliary movement, behavior of coronal cells, plume cells, sweepers 1 and 2 could be viewed only by the use of a high-speed camera. Mohican, fright, apical, and oral cells were less active. Seven types of interior cells were identified: parenchymal cells, blastema cells, neck and roof cells from the internal sac, glandular cells from the pyriform-glandular complex, small pigmented cells, and muscles. Detailed descriptions were made of individual cell morphology and behavior. After transfer to culture media, many dissociated cells adhered to clean glass surfaces where they maintained their morphology and behavior for at least 2 days. Some cells extended processes during culture, suggesting the neuronal origin of these cells. The cell bodies of glandular cells were suitable for patch-clamp study. These results are discussed in relation to previous ultrastructural studies of B. neritina, with particular reference to the potential functionality of cells. © 1996 Wiley-Liss, Inc.