Stage 17 (1 day 1 hr)
Early neurula stage (Head formation)
Drown by T. Iwamatsu
(Abbr. bl: beak-like mass of cells, em: embryonic body, kv: Kupffer's vesicle)
Stage 17 (1 day 1 hr) Early neurula stage (Head formation):
The yolk sphere is nearly covered by the thin blastoderm leaving a small area around the vegetal pole (yolk plug) exposed. Thehead (rudimentary brain) is recognized anteriorly in the distinct embryonic body. A beak-like mass of cells is seen in front of the head. A fewsmall vacuoles (Kupffer's vesicles) appear at the underside of the caudal (posterior) end of the body, which is in contact with a small blastopore.