Editing Thymus (section)

===Microanatomy===
The thymus consists of two lobes, merged in the middle, surrounded by a capsule that extends with blood vessels into the interior.<ref name=Grays2016>{{cite book |title=Gray's Anatomy: The Anatomical Basis of Clinical Practice | editor-first1 = Susan | editor-last1 = Standring | editor-first2 = Henry | editor-last2 = Gray | name-list-style = vanc  |isbn= 9780702052309 |edition=41st |location=Philadelphia |oclc=920806541 |year=2016 |pages=983–6 }}</ref> The lobes consist of an outer {{wt|en|cortex}} rich with cells and an inner less dense {{wt|en|medulla}}.<ref name="Wheaters2013" /> The lobes are divided into smaller lobules 0.5-2 mm diameter, between which extrude radiating insertions from the capsule along {{wt|en|septa}}.<ref name=Grays2008 />

The cortex is mainly made up of [[thymocyte]]s and epithelial cells.<ref name="Robbins9th" /> The thymocytes, immature [[T cells]], are supported by a network of the finely-branched [[epithelial reticular cells]], which is continuous with a similar network in the medulla. This network forms an [[adventitia]] to the blood vessels, which enter the cortex via septa near the junction with the medulla.<ref name=Grays2008/> Other cells are also present in the thymus, including [[macrophage]]s, [[dendritic cell]]s, and a small amount of [[B cell]]s, [[neutrophil]]s and [[eosinophil]]s.<ref name="Robbins9th" />

In the medulla, the network of epithelial cells is coarser than in the cortex, and the lymphoid cells are relatively fewer in number.<ref name=Grays2008 /> Concentric, nest-like bodies called [[Hassall's corpuscles]] (also called ''thymic corpuscles'') are formed by aggregations of the medullary epithelial cells.<ref name="Robbins9th" /> These are concentric, layered whorls of [[epithelial cell]]s that increase in number throughout life.<ref name=Grays2008 /> They are the remains of the epithelial tubes, which grow out from the third [[pharyngeal pouch (embryology)|pharyngeal pouches]] of the embryo to form the thymus.<ref>{{cite book |vauthors = Larsen W |title=Human Embryology |date=2001 |publisher=Elsevier |isbn=978-0-443-06583-5 |pages=366–367 |edition=3rd}}</ref>

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File:Thymus.JPG|[[Micrograph]] showing a lobule of the thymus. The cortex (deeper purple area) surrounds a less dense and lighter medulla.
File:Thymic corpuscle.jpg|Micrograph showing a Hassall's corpuscle, found within the medulla of the thymus.
</gallery>