part of part of develops_from embryo pharyngeal arch 1 developing anatomical structure lingual swellings median lingual swelling During the third week of embryological development there appears, immediately behind the ventral ends of the two halves of the mandibular arch, a rounded swelling named the tuberculum impar, which was described by His as undergoing enlargement to form the buccal part of the tongue. More recent researches, however, show that this part of the tongue is mainly, if not entirely, developed from a pair of lateral swellings which rise from the inner surface of the mandibular arch and meet in the middle line. The site of their meeting remains post-embryonically as the median sulcus of the tongue. The tuberculum impar is said to form the central part of the tongue immediately in front of the foramen cecum, but Hammar insists that it is purely a transitory structure and forms no part of the adult tongue[WP, Gray's]. VHOG:0000730 The thyroid initially develops caudal to the tuberculum impar . This embryonic swelling arises from the first pharyngeal arch and occurs midline on the floor of the developing pharynx, eventually helping form the tongue as the 2 lateral lingual swellings overgrow it. [http://emedicine.medscape.com/article/845125-overview] tuberculum impar FMA:312476 median tongue bud tuberculum linguale mediale uberon Most adult amphibians have a tongue, as do all known reptiles, birds and mammals. Thus it is likely that the tongue appeared with the establishment of tetrapods and this structure seems to be related, to some extant, to the terrestrial lifestyle.[well established][VHOG] EMAPA:17187 EHDAA2:0001081 median lingual swelling UBERON:0006756