Isolation and morphofunctional characterization of mussel digestive gland cells in vitro.

The aim of the present study was to isolate and characterize digestive gland cells of the bivalve mollusc Mytilus galloprovincialis Lmk. The digestive gland of bivalves is a complex organ composed of digestive and connective tissues but it is also invaded by the reproductive tissue as gametogenesis proceeds. The digestive tissue is comprised of stomach and intestinal epithelial cells, ciliated and non-ciliated duct cells, digestive cells and basophilic cells. the last two cell types are found lining the epithelium of the blind-ending digestive tubules and are the main focus of this study. Two different approaches were assayed for cell isolation, i.e., explant culture techniques and mechanical plus enzymatical digestion techniques. Cell viability was tested by trypan blue exclusion, neutral red uptake and ultrastructural analysis. The explant cultures were often contaminated with bacteria and spermatozoa and, moreover, cells migrating out of the explants possibly corresponded to hemocytes and not to digestive tissue cells. Mechanical plus enzymatical digestion with collagenase was concluded to be the method of choice for digestive cell isolation, with a percentage of about 30% of isolated cells corresponding to digestive cells. The ultrastructure of digestive cells isolated with the latter procedure closely resembled that of mussel digestive cells in vivo.