immediately_preceded_by developmental stage Medaka stage 28 Medaka stage 29 34 somite stage Internal ear formation OlatDv:0000320 Zoological Science 11: 825-839 (1994) - 3 days 2 hrs Stage 29 (3 days 2 hrs) 34 somite stage (Internal ear formation): The embryonic body encircles about 3/4 of the yolk sphere. The anlage of the pineal gland is recognized as a disc-shaped, round structure at the dorsal surface of the 3rd ventricle. In the heart, the sinus venosus, atrium, ventricle and bulbus arteriosus are differentiated. There is a large, transparent membranous protrusion inside the outer wall and another inside the inner wall of the otic vesicle (internal ear formation). In the region posterior to the eye (where gills will form), a group of large hatching enzyme cells has differentiated from endodermal cells [7,28]. A ventral eminence is prominent behind the otic vesicles, and an- other eminence (the presumptive swim bladder) is discernible at the ventral side of the 3rd somite. The pectoral fin is apparent, and membranous fins are also seen in the tail, which has 19 somites beyond the gut tube. Guanophores begin to disperse on the dorsal surface of the body trunk. The anterior tip of the notochord is located where the branches of the dorsal aorta join. - 3 days 2 hrs medaka_ontology