part of part of has developmental contribution from transformation of endocrine system thyroid gland (...) at some stage of its development, every chordate exhibits five uniquely derived characters or synapomorphies of the group: (...) (2) a groove in the pharyngeal floor known as the endostyle, or a thyroid gland derived from part of the endostyle (...).[well established][VHOG] A two-lobed endocrine gland found in all vertebrates, located in front of and on either side of the trachea in humans, and producing various hormones, such as triiodothyronine and calcitonin[BTO]. AAO:0010544 BTO:0001379 CALOHA:TS-1047 EFO:0000861 EHDAA2:0002028 EHDAA:2148 EHDAA:2975 EMAPA:17068 EV:0100133 Either of paired structures located in the throat which develop from the ventral wall of the pharynx and excretes hormones involved in the morphological and functional changes during metamorphosis as well as influencing other tissues.[AAO] FMA:9603 GAID:465 In fish, it is usually located below the gills and is not always divided into distinct lobes. However, in some teleosts, patches of thyroid tissue are found elsewhere in the body, associated with the kidneys, spleen, heart, or eyes In larval lampreys, the thyroid originates as an exocrine gland, secreting its hormones into the gut, and associated with the larva's filter-feeding apparatus. In the adult lamprey, the gland separates from the gut, and becomes endocrine, but this path of development may reflect the evolutionary origin of the thyroid. For instance, the closest living relatives of vertebrates, the tunicates and Amphioxus, have a structure very similar to that of larval lampreys, and this also secretes iodine-containing compounds (albeit not thyroxine) In tetrapods, the thyroid is always found somewhere in the neck region. In most tetrapod species, there are two paired thyroid glands - that is, the right and left lobes are not joined together. However, there is only ever a single thyroid gland in most mammals, and the shape found in humans is common to many other species MA:0000129 MAT:0000081 MESH:D013961 MIAA:0000081 OpenCyc:Mx4rvVjLT5wpEbGdrcN5Y29ycA UBERON:0002046 UMLS:C0040132 VHOG:0000418 XAO:0000162 galen:ThyroidGland glandula thyroidea thyroid uberon neural crest endocrine gland endoderm-derived structure thyroid diverticulum structure with developmental contribution from neural crest