Expression of ClpostHox in embryos and juveniles of C. longifissura. (a) Vegetal view on the site of gastrulation. ClpostHox expression begins at the vegetal pole of the postgastrula stage of C. longifissura. (b) Lateral view on the later embryo with the ClpostHox expression in the vegetal hemisphere. Asterisk indicates the animal pole. (c) ClpostHox expression is located in the posterior end in all three germ layers of pre-hatchlings. Cellular differentiation is indicated by the appearance of the statocyst (st). (d) Dorsal view on the hatched juvenile with fading ClpostHox expression. Localized centers of expression remain visible (black arrowheads). (e) Lateral view of a hatched juvenile of C. longifissura showing strong ClpostHox expression in individual cells in an area of weaker expression, anterior to the left. (f) + (g) Summary expression of ClpostHox (blue) in juveniles. Note that the posterior most tip of the animal is free of expression. Anterior to the left.