immediately_preceded_by developmental stage Medaka stage 35 Medaka stage 36 OlatDv:0000390 Zoological Science 11: 825-839 (1994) - 6 days Stage 36 (6 days) Heart development stage: The tip of the tail reaches the otic vesicle. Guanophores and melanophores are distributed on the dorsal wall (peritoneum) of the peritoneal cavity beneath the 1st to the 4th somites. The extent of flexion of the atrio-ventricular region of the heart increases so that in a lateral view, the atrium and the ventricle lie adjacent to each other. - 6 days heart development stage medaka_ontology