Reticular cells originating from an embryonic epithelium are found in the:
a. Bronchiolar associated lymphoid tissue (BALT) of the respiratory system
b. Lymph nodes
c. Spleen
d. Thymus
e. Tonsils
ANS: D
Reticular cells of the thymus, unlike those of other lymphoid organs, originate from the endo-dermal epithelium of the branchial pouches. Genetic abnormalities in these and other epithelia are found in the nude mouse, a strain of mouse that cannot grow hair on its epidermal epithelium and cannot attract lymphocytes to colonize the abnormal epithelium of the thymus. These mice have a nonfunctioning thymus, cannot produce normal T cells, and cannot reject tissue trans-plants from other mice.
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Fill in the blank(s) with the appropriate word(s).
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