Fig. 2. Colorized confocal sections taken from whole-mounted phalloidin-stained Boltenia villosa embryos at selected stages. Dorsal is always up. In top and side views, anterior is to the left and posterior to the right. Red=primary notochord lineage; violet=secondary notochord lineage; dark blue=neural plate; orange=posterior muscle; light brown=mesenchyme/trunk lateral cells; yellow=endoderm/endodermal strand; light blue=epidermis. Scale bar, 10 µm in all panels. The above also refers to Fig. 3 and Fig. 5. A late gastrula stage embryo (approx. 15 hours AF). (A) Raw confocal data before false coloring to produced B; (B) Top view; (C) Lateral view. Several cells within the primary notochord lineage have just begun to cleave (asterisks). Secondary notochord lineage cells (violet) lie at the ends of the notochord plate just anterior to the posterior muscle. Note that apices of individual cells forming the anterior portion of the blastopore lip have not yet begun to constrict.