Figure 5.

Community effect does not override cell identity in E12.5 TEC progenitors. E11.5 mGFP⁺PLET1⁺, E12.5 mGFP⁺PLET1⁺ or E13.5 UEA1⁺ TEC were isolated. A defined number of mGFP⁺ TEC was then injected into the lumen of E11.5 (A) or the body of wild type E12.5 (B,C) thymic primordia. The injected primordia were grafted under the kidney capsule of recipient mice on the same day that they were microdissected and within 2 hours of microinjection. Grafts were recovered after 2-3 weeks and analyzed by histology and immunohistochemical analysis with the markers shown. (A) Images show representative mGFP⁺ foci in grafts of E11.5 thymic lobes into which forty E12.5 mGFP⁺PLET1⁺ cells were injected in the lumen. mGFP⁺ foci are negative for cytokeratin 14 (K14) and positive for Ly51. (B) Images show representative mGFP⁺ foci in a graft in which twenty E13.5 mGFP⁺UEA1⁺ TEC were injected into the body of an E12.5 lobe. mGFP⁺ cells were located in the medulla region or the CMJ. (C) Images show representative mGFP⁺ foci in graft in which thirty E11.5 mGFP⁺PLET1⁺ TEC were injected into the body of an E12.5 lobe. mGFP⁺ cells were located only in the cortical region. (A–C) Graft names correspond to the graft identities in Table 2 . Scale bars, (A) A 75µm except bottom right panel, 300µm. (B) 75µm (C) 55µm. N for each condition represents an independent graft and is as indicated in Table 2 ; at least three biologically independent replicates were performed for each injection condition.