Figure 1
![Figure 1. Development of immune profile in fetal thymus by immunohistochemistry. (A,C,E; ×20, H&E) Shows the evolution in tissue architecture, as well as the appearance and expansion of CD4/8 DP cells (B,D,F; ×20, CD4+ [blue], CD8+ [red], CD4/8 DP [purple]). At 33 days (A-B), the thymus is relatively devoid of T cells or their precursors. By 39 days (C-D), DP cells begin to appear and undergo significant expansion by 46 days (E-F), when the tissue architecture takes on a relatively normal postnatal appearance. Scale bars represent 50 μm. Flow cytometry (G) confirms rapid proliferation of DP thymocytes between 39 and 42 days, with even more significant increase by 46 days.](https://ash.silverchair-cdn.com/ash/content_public/journal/blood/124/12/10.1182_blood-2013-11-537571/4/1987f1.jpeg?Expires=1723248943&Signature=zluIdzVxe7DqPBxUQ5jGhXo9cJWCRZCIbEe9zfgZ3R5vLPkGs7-vC8Qk0WNUZ-Ks9~2N6cEhBhybGNWEvxFTGIROHI8NOgEEH-TvxPNO4qtobqMUPRP8wo225J3i6IPF41How92zL2pEo6nq3eGqAj9Wsg8Qxn-AIEFsFbcw0OH4JSeLrmrP8jlcg9q0eUERW-36ByxaUrImMOJN87ZwmgM52KWC447Juqo41I8MCzmzRneauBtZ46L909pWw~6R9nP0WBOazt2Z06x42~cYwagZ1Hg0CmQ1eVVdS4ZEshoOzppQqs8Q05UHsUvpS9cIhN3mobVeNMYRPOAdkxvaTA__&Key-Pair-Id=APKAIE5G5CRDK6RD3PGA)
Development of immune profile in fetal thymus by immunohistochemistry. (A,C,E; ×20, H&E) Shows the evolution in tissue architecture, as well as the appearance and expansion of CD4/8 DP cells (B,D,F; ×20, CD4+ [blue], CD8+ [red], CD4/8 DP [purple]). At 33 days (A-B), the thymus is relatively devoid of T cells or their precursors. By 39 days (C-D), DP cells begin to appear and undergo significant expansion by 46 days (E-F), when the tissue architecture takes on a relatively normal postnatal appearance. Scale bars represent 50 μm. Flow cytometry (G) confirms rapid proliferation of DP thymocytes between 39 and 42 days, with even more significant increase by 46 days.
