Fig. 3.

Oral marker gene expression is mostly restricted to developing oral regions in polyps and medusae of Clytia hemisphaerica and Aurelia aurita. (a) Expression of Ch-bra1 in the mouth endoderm. (b–d) During medusa formation, it is expressed from the earliest budding stages onwards, initially in the entire entocodon, then restricted to the oral ectoderm. In late medusa buds and the medusa, Ch-bra1 is restricted to the mouth endoderm. (e) Ch-foxA expression in the entire head endoderm in polyps but absent from the tentacles. (f–h). During medusa formation, the onset of Ch-foxA expression coincides with the appearance of the mouth tube. In later medusa buds and in the free medusa, the entire mouth tube apart from the mouth tip region is foxA-positive. (i) Ch-otp expression in the polyp ectodermal mouth region and in single cells in the tentacles. In early medusa budding stages (k), Ch-otp is expressed in cell clusters in the developing oral ectoderm and in single cells in the outer bud ectoderm. In late medusa budding stages and medusa the oral expression of otp becomes more prominent and numerous otp-positive cells and cell clusters appear at the bell rim and at the aboral side of the tentacle bulbs and single cells at the bell rim. (n–q) Schematics illustrate oral marker gene expression in the representative stages of Clytia. (r) Aurelia ephyra show Aa-bra1 expression in the mouth tip. s Aaotp expression in single cells of the rhopalar arm ectoderm and the mouth tip. (t) AafoxA expression in the entire mouth tube of the ephyra but not in the lips (u) Schematic shows summary of mouth marker expression in the Aurelia ephyra