Anatomy of a larval tunicate showing the placement of the endostyle
The endostyle is an organ in the pharynx of chordate animals that assists in filter-feeding, and is found in adult cephalochordates (lancelets) and urochordates (sea squirts, salps and larvaceans), as well as in the larvae of some basal vertebrates (specifically the lampreys),[1] but has been transformed through evolution into the thyroid in other vertebrates. It is one of the five common anatomical features (synapomorphies) found in all chordates, along with the notochord, dorsal nerve cord, pharyngeal slits and a post-anal tail.
Since the endostyle is found in all three chordate lineages, it is presumed to have arisen in the common ancestor of these taxa, along with a shift to internal feeding for extracting suspended food particles from the water.[2] When feeding, food particles suspended in the water adhere to the mucus the endostyle produces.[3] The filtered water is then expelled through the gill slits, while the food and mucus are swept into the esophagus by movements of the cilia that coat the endostyle.[3][4]
The endostyle in larval lampreys (ammocoetes) metamorphoses into the thyroid gland in adults, and is regarded as being homologous to the thyroid in all other vertebrates due to its iodine-concentrating activity.[5]
Early beliefs of the endostyle included the idea by Muller in 1873 stating that the endostyle that reside in the ammocoete has extremely similar functions as the protochordate hypobranchial groove. Thus, numerous investigations into the endostyle ensued, only for the theory to be denied by future researchers. However, during this research, it was found that ammocoete endostyles include the capability and functionality to accumulate radioactive iodine isotopes. This once again made the endostyle a very pertinent topic of research by a multitude of scientists. Recent research has concluded that cephalochordate and tunicate endostyles have the ability to capture iodine, thus further perpetuating new research.[4]
^"Endostyle - an overview | ScienceDirect Topics". www.sciencedirect.com. Retrieved 2021-01-05.
^Dumont, Jacques; Opitz, R.; Christophe, D.; Vassart, Gilbert; Roger, P.P.; Maenhaut, C. (30 November 2011). "Ontogeny, Anatomy, Metabolism and Physiology of the Thyroid". Endotext [Internet]. PMID 25905409.
^ abL., Jordan, E. (1967). Chordate Zoology. Delhi: S. Chanda & Co. ISBN 81-219-1639-9. OCLC 712010960.{{cite book}}: CS1 maint: multiple names: authors list (link)
^ abOlsson, Ragnar (September 1963). "Endostyles and endostylar secretions: A comparative histochemical study". Acta Zoologica. 44 (3): 299–328. doi:10.1111/j.1463-6395.1963.tb00411.x.
^Ogasawara, Michio; Di Lauro, Roberto; Satoh, Nori (1 June 1999). "Ascidian Homologs of Mammalian Thyroid Transcription Factor-1 Gene Are Expressed in the Endostyle". Zoological Science. 16 (3): 559–565. doi:10.2108/zsj.16.559. hdl:2433/57227. ISSN 0289-0003. S2CID 27892843.
The endostyle is an organ in the pharynx of chordate animals that assists in filter-feeding, and is found in adult cephalochordates (lancelets) and urochordates...
These five synapomorphies are a notochord, a hollow dorsal nerve cord, an endostyle or thyroid, pharyngeal slits, and a post-anal tail. The name "chordate"...
long ciliated groove, or endostyle, runs along one side of the pharynx, and a projecting ridge along the other. The endostyle may be homologous with the...
an endostyle, an organ used for filter feeding that is otherwise found only in tunicates and lancelets. During metamorphosis the lamprey endostyle develops...
all chordates, the other four being a notochord, a post-anal tail, an endostyle, and pharyngeal slits. The dorsal nerve cord is located dorsal to the...
opening with the rest of the gut. It has a ciliated groove known as an endostyle on its ventral surface, and this secretes a mucous net which collects...
five synapomorphies are pharyngeal slit, dorsal nerve cord, notochord, endostyle, and the post-anal-tail which is depicted and labeled well on the chordates...
series of tongue-shaped dorsal languets that help transport food, while an endostyle, another organ assisting in filter-feeding, is present on the front side...
secreted by parafollicular cells (also known as C cells) of the thyroid (or endostyle) in humans and other chordates in the ultimopharyngeal body. It acts to...
perforated by many vertically elongated, pharyngeal slits ... Cells in the endostyle of the pharyngeal floor secrete mucus that entraps minute food particles...
pharyngeal arches, as well as an iodine-concentrating organ called the endostyle, which develops into the thyroid in adults. With only one exception, the...
the lamprey loses both the gallbladder and the biliary tract, and the endostyle turns into a thyroid gland. Some species, including those that are not...
constituent of hagfish slime used to deter predators. Mucus is produced by the endostyle in some tunicates and larval lampreys to help in filter feeding. Biology...
Fritillariidae in the putative Endostyla, based on the presence of an endostyle, absent in Kowalevskia which he placed in the sister group Anendostyla...
anatomical features of the adult amphioxus (hollow dorsal nerve tube, endostyle, segmented body, postanal tail). De Quatrefages first completely described...
(c) tunic or test (d) mantle; (e) branchial sac; (f) gullet; (g) stomach; (h) anal orifice; (i) dorsal lamina; the dotted line indicates the endostyle....
Olfactores. Ancestral chordates evolved a post-anal tail, notochord, and endostyle (precursor of thyroid). The pharyngeal slits (or gills) are now supported...
branchial sac with gill slits. Along the side of the branchial sac runs the endostyle, which produces mucus filters. Water is moved through the gill slits into...
(lancelets), have a structure very similar to that of larval lampreys (the endostyle), and this also secretes iodine-containing compounds, though not thyroxine...
branchial sac with gill slits. Along the side of the branchial sac runs the endostyle, which produces mucus filters. Water is moved through the gill slits into...
circulatory system is powered by the beating tail. Kowalevskia also lacks an endostyle, being replaced by a ciliated groove without glandular cells. The spiracles...
interspersed by white, translucent patches. A stolon grows from near the endostyle (an elongated glandular structure producing mucus for trapping food particles)...
running close to the ventral and posterior margins is interpreted as an endostyle. The condition of the anterior portion of the fossils suggests that it...
homologous to those of vertebrates such as the pronephric kidney or an endostyle (ciliated, grooved organ that aids in filter feeding via production of...
and other small organisms get trapped in mucus threads secreted by the endostyle. The tunicate seems to form a symbiotic relationship with the bryozoan...
from the incurrent siphon, with the help of the endostyle using cilia. Mucus glands in the endostyle secrete mucus used to filter through the incoming...
interior surface of the anterior section, which they speculate is an endostyle. Palaeontology portal Maotianshan shales Shu, D. -G.; Conway Morris, S...
has a small lower lip and the buccal glands are small and globular. The endostyle is large, extending nearly as far as the anus. The right lobe of the stomach...
wheel organ, Hatschek's pit, and the tracts in the pharynx called the endostyle and epibranchial groove. "Cephalochordata, Laboratory Notes for BIO 1003"...
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