Expression patterns of CheSox1, CheSox3, CheSox10 and CheSox12 in the medusa. (A-D) Single in situ hybridisation in the medusa tentacle bulbs for CheSox1 (A), CheSox3 (B), CheSox10 (C) and CheSox12 (D). These four genes are expressed in two symmetrical patches at the proximal pole of the tentacle bulb. (E-H) Double in situ hybridisations of these four Sox genes (in blue) with the stem cell marker Piwi (in red) in the tentacle bulb. In the four cases, staining is homogeneously purple, indicating co-expression of the genes. (I-L) Double in situ hybridisations of the four Sox genes (in blue) with Minicollagene 3-4 (mcol3-4a) (in red), a marker of nematocyte differentiation. Most CheSox1, CheSox3, CheSox10 and CheSox12 positive cells do not express mcol3-4a. In A-L, tentacle bulbs are oriented with their proximal pole on the top; the star indicates the base of the tentacle. (M-P) Gene expression in the manubrium (lateral orientation, with mouth on the bottom, mo) for the same four Sox genes. No signal was detected for CheSox1 (M), CheSox3 (N) and CheSox12 (P) whereas CheSox10 (O) is strongly expressed in the ectoderm of the four longitudinal ridges of the manubrium. (O') detailed view of the area boxed in O. Black arrowheads point to stained cells, showing a typical neuronal morphology. (Q-T) Expression in the female gonad of CheSox1 (Q), CheSox3 (R), CheSox10 (S) and CheSox12 (T). These four genes are expressed in maturating oocytes (ov). Scale bars: A-L, 20 μm; M-T, 50 μm; O', 2 μm.