immediately_preceded_by developmental stage Medaka stage 21 Medaka stage 22 9 somite stage Appearance of heart anlage OlatDv:0000250 Zoological Science 11: 825-839 (1994) - 1 day 14 hrs Stage 22 (1 day 14 hrs) 9 somite stage (Appearance of heart anlage): The tubular heart (heart anlage) appears underneath the head from the posterior end of the mid-brain to the anterior end of the hind-brain. The anlage of the hatching enzyme gland (cell mass) appears at the centroventral side of the hind-brain [28]. The body cavity extends further toward the posterior end of the eye vesicles. Melanophores appear on the yolk sphere. Incomplete lenses are present in the eyes, and the vesicular otocyst is defined. - 1 day 14 hrs medaka_ontology