Starting at embryonic day 9.5, development of a subset of these cells is driven by Pax1 expression, and these cells also require Hoxa3 after day 11 for sustained growth. One class of these cells uses the zinc finger protein FezF2 to help carry out a “promiscuous” process with adjacent developing cells. Transgenic mice for studying these cells are frequently controlled by a Foxn1 promoter. Deficiencies in at least one class of these cells will impair formation of (*) Hassall’s corpuscles. A mature class of these cells presents tissue-restricted antigens to one class of developing lymphocytes via the protein AIRE. That class of these cells is named for their location in the medulla of a naturally involuting organ, as opposed to their cortical counterparts that regulate positive selection. For 10 points, name these stromal cells from a namesake organ that mediate multiple key steps in T-cell development. ■END■
ANSWER: thymic epithelial cells [or medullary thymic epithelial cells; or cortical thymic epithelial cells; or thymus epithelial cells; accept TECs (“teks”); accept mTECs (“M-teks”) or cTECs (“C-teks”); accept junctional thymic epithelial cells or jTECs (“J-teks”); accept thymic tuft cells; prompt on epithelial cells by asking “in which organ?”] (The clues in order refer to: thymic tuft cells, mTECs, PGE and AIRE+ mTECs, all TECs broadly, jTECs/mTECS, just mTECs, cTECs, TECs generally.)
<RH, Biology>
= Average correct buzz position