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consist of accumulations of lymphocytes afferent lymphatic vessels, instead relying
on their proximity to the epithelial sur-
(in this location called thymocytes); it is
VetBooks.ir within the thymus that embryonic lym- face to make contact with antigens. Many
tonsils are characterized by deep invagi-
phocytes undergo differentiation and leave
to populate the many other lymphatic nations on their epithelial surfaces called
tissues of the body. crypts, which presumably increase the
surface area for contact with lymphatic
tissue. Although the word tonsil is usually
Tonsils reserved for the lymphatic organs associ-
ated with the pharynx, identical histolog-
In the most traditional sense, a tonsil is ical elements are found in the mucous
an unencapsulated aggregate of lym- membranes of the prepuce and vagina
phatic nodules associated with the phar- and in the submucosa of the intestinal
yngeal mucosa. These aggregates lack tract.