Expression pattern of Nv-CBFβ in adult Nematostella. A Digoxygenin-labeled riboprobe corresponding to nucleotides 56–434 was used. A) CBFβ is expressed in the tentacles and mouth region of adult anemones. No staining could be seen when a control probe from the sense strand was used (right animal). B) An inset from A, showing strong expression in the tentacle tips (arrow). C) Expression of CBFβ in the mouth and extended upper pharynx of the same animal as depicted in A and B. Expression levels in the mouth region differed between different animals. D) General architecture of the tentacles and mouth region, showing the location of the enlarged micrographs in E and H (panel H is of a different serial section from the same anemone). Ten = tentacle, phx = pharynx. Scale bar = 100 μm. E, F) Expression of CBFβ at the base of the ectoderm of the tentacles (arrowheads) en = endoderm, ec = ectoderm, mes-mesoglea. Bar in E = 100 μm, in F = 20 μm. G) Expression of CBFβ in the ectoderm of the mouth (arrows). en = endoderm, ec = ectoderm, mes-mesoglea, gvc = gastrovascular cavity. Bar = 100 μm H) Enlargement of a region in the mouth, showing the CBFβ expression in cells close to large microbasic mastigophore nematocysts (arrowheads) Bar = 20 μm. I) Thin (2 μm) epoxy cross section through the mouth region stained with Methylene Blue, revealing the secretory gland cells (gc) and abundance of microbasic mastigophore nematocytes (mbm) of different sizes. Bar = 20 μm.