Fig. 9.

Expression of sfrp1/2/5 during early development in Platynereis. a–d, b′–d′ WMISH of sfrp1/2/5, and a′, b″–d″ false color images of WMISH (red) overlaid with DAPI-stained nuclear images (blue). a, a′ 6 hpf embryo, animal-pole view. White arrowheads indicate 1q¹¹ cells. b, b′, b″ 8 hpf embryo focusing on animal pole (b) and mid-section (b′) of embryo. Expression in rosette cells can be seen at the animal pole in b and b″. White arrowheads indicate more vegetal expression domains in a, b and d quadrants, likely in the 3q lineage. c Quadrant expression is not yet distinct. c, c′, c″ 10 hpf embryo with an animal-pole view focusing on animal pole in c, and mid-section view in c′. Expression throughout 1q¹¹ progeny can be seen at animal pole in c and c″. White arrowheads indicate expression in 3q lineage in all four quadrants. d, d′, d″ 10 hpf embryo side view from c quadrant showing shallow focus (d) and deeper focus (d′). d Quadrant is to the left, and b quadrant is to the right. White asterisks indicate animal pole. Black arrows indicate direction of dorsal–ventral (D-V) and animal-vegetal (A-V) axis