This site of positive and negative selection involutes during puberty.
Malignancies of this organ are staged according to the Masaoka system. One class of cells that develop in this organ recognizes the protein R3G1. Mutations in a transcription factor ubiquitously expressed in epithelial cells of this organ's medulla result in a disease that manifests as a poly-endo-crinopathy along with muco-cutaneous candi-diasis and Addison's disease. A functional second cervical version of this organ has been identified in mice. Hassall's corpuscles are found in this organ. It is absent in a disease caused by a deletion along the long arm of chromosome 22, called DiGeorge syndrome. Upregulation of the FOXN1 gene allows regeneration of this organ, and deletion of the same gene causes absence of this organ in nude mice. Tumors in this organ are commonly found in patients with myasthenia gravis. Double positive cells in this organ mature to express either CD4 or CD8. This site of positive and negative selection involutes during puberty. For 10 points, name this site of T-cell maturation.
Malignancies of this organ are staged according to the Masaoka system.
thymus