Stage 24 (1 day 20 hrs)
16 somite stage (Start of heart beating)
Drown by T. Iwamatsu
(Abbr. bi: blood island, cd: Cuvierian duct, ch: chorion, ea otic (ear) vesicle, gt: gut tube, h: heart rudiment)
Stage 24 (1 day 20 hrs) 16 somite stage (Start of heart beating):
The anterior portion of the heart, which exhibits a slow (about 33-64/min) pulsation, extends up to the anterior end of the fore-brain. Cuvierian ducts and the vitello-caudal vein are still incomplete. Kupffer's vesicles have almost disappeared. Otoliths are not yet present in the otic vesicles. The embryonic body
encircles nearly 1/2 of the yolk sphere. The gut (digestive) tube is observed ventral to the dogleg-shaped somites.