Endostyle

An endostyle is a longitudinal ciliatedgroove on the ventralwall of the pharynxwhich produces mucusto gather food particle. It is found in urochordatesand cephalochordates, and in the larvae of lampreys. It aids in transporting food to the esophagus. It is also called the hypopharyngeal groove. The endostyle in larval lampreys (ammocetes) metamorphoses into the thyroidgland in adults, and is regarded as being homologous to the thyroid gland in vertebrates.

Since the endostyle is found in the three branches of chordates, it is presumed to have arisen in the common ancestor of these taxa, along with a shift to internal feeding for extracting suspended food from the water.

References

• Marine, David. 1913. The Metamorphosis of the Endostyle (Thyroid Gland) of Ammocoetes branchialis (Larval Land-Locked Petromyzon marinus (Jordan) or Petromyzon dorsatus (Wilder), The Journal of Experimental Medicine, 17:379-395. [1]- accessed November 312005
• Ogasawara, M. and Satoh, N. 1998. Isolation and Characterization of Endostyle-Specific Genes in the Ascidian Ciona intestinalis, The Biological Bulletin, 195:60-69. [2]- accessed November 312005
• Dumont, J. E., Corvilain, B., and Maenhaut, C. 2002. Chapter 1: The Phylogeny, Ontogeny, Anatomy, and Metabolic Regulation of the Thyroid, Thyroid Disease Manager. [3]- accessed November 312005

This article is licensed under the GNU Free Documentation License.
It uses material from the http://en.wikipedia.org/wiki/Endostyle Wikipedia article Endostyle.