St18-8.8hpf

initial tailbud II (8.8 hours), the tail is clearly separated from the trunk. Tail and trunk have same length. The neuropore is still opened and the A-line neurulation is observed. The tail also begins to bend.

 

Three-dimensional images (upper) and cross-section images (lower). Anterior is left in all panels. Arrow indicates the position of pigment cells. Arrowheads indicate the cilia of epidermal sensory neurons. b.p., blastopore; n.p., neuropore; epi, epidermis; ec, endodermal cavity; en, endoderm; es, endodermal strand; b, brain; mu, muscle; g, germ line cells; noto, notochord; n.t., neural tube; ec, endodermal cavity; t.epi.m-l.r, tail epidermis medio-lateral row; t.epi.m.r, tail epidermis medial row; t.epi.l.r, tail epidermis lateral row; va, vacuole; p, palps. In I, embryo direction is shown by A: anterior, P: posterior, D: dorsal, V: ventral. Scale bar = 50 micro m.