Oikopleura genes expressed throughout the tail. (A-U) Oikopleura embryos hybridized in situ with antisense probes for the genes indicated at the bottom right of each row. The developmental stages are indicated in the column headings; all embryos are oriented with anterior to the left and dorsal up, with the exception of the embryos in panels (N) and (T), which are shown as dorsal views. Pink arrowheads indicate the notochord in all embryos showing diffuse expression throughout the tail.
Kugler et al. BMC Evolutionary Biology 2011 11:21 doi:10.1186/1471-2148-11-21