Cells have been cultured from the rectal gland, eye, brain, kidney and early embryo of Squalus acanthias. Medium is either LDF, developed for zebrafish cells (Barnes and Collodi 2005) or VCM (Valentich and Forrest 1991) , a urea-timethylamine oxide (TMAO)-containing medium that supports the short-term culture of shark rectal gland cells. In some cases cells are plated onto dishes pretreated with collagen. Medium is further supplemented with a variety of cell typespecific peptide growth factors, nutrients and purified proteins at a range of concentrations. These include insulin, transferrin, epidermal growth factor (EGF), basic fibroblast growth factor (FGF), transforming growth factor-beta, vitamins A and E, selenium, mercaptoethanol, dexamethasone, fetal calf serum, shark serum and shark yolk extract. For example shark brain cells can be grown in primary culture in VCM containing EGF, FGF, insulin, transferrin, selenium, a chemically-defined lipid supplement and vitamin E on a fibronectin substratum (Figure 1 ). Expression of genes from plasmids has been achieved in primary dogfish shark rectal gland cell cultures by lipofection using the CMV promoter to direct expression of the gene of interest ( Figure 2 ). Differentiated function also is maintained, as evidenced by expression of CFTR and vasoactive intestinal peptide receptor (VIPR) mRNA detected by reverse-transcription polymerase chain reaction (RT-PCR) assay (Figures 3  and 4) .