Haynes B F
Department of Medicine, Duke University Medical Center, Durham, NC 27710.
Thymus. 1990 Nov-Dec;16(3-4):143-57.
The human thymus develops early in fetal gestation with morphologic maturity reached by the beginning of the second trimester. TE3+ cortical thymic epithelium is most likely derived from endodermal third pharyngeal pouch, while A2B5/TE4+ medullary and subcapsular cortical thymic epithelium is likely derived from third pharyngeal cleft ectoderm. Fetal liver and yolk sac CD7+, CD4-, CD8-, surface(s) CD3- T cell precursors begin to colonize the thymus between 7 and 8 weeks of fetal gestation, followed by rapid expression of other T lineage surface molecules on developing thymocytes. CD7+, CD4-, CD8-, sCD3- thymocytes give rise to T cells of both the TCR alpha beta and TCR gamma delta lineages. Human thymic epithelial cells produce numerous cytokines including IL1, IL6, TGF alpha, leukemia inhibitory factor (LIF), M-CSF, G-CSF and GM-CSF- molecules that likely play important roles in multiple stages of thymocyte selection, activation and differentiation. Important areas for future research on human thymic epithelium include study of lymphoid and non-lineage differentiation potentials of CD7+, CD4-, CD8-, sCD3- T cell precursors in response to TE-cell produced cytokines, study of the triggering signals of cytokine release within the thymic microenvironment, and study of TCR-MHC mediated TE-thymocyte interactions.
人类胸腺在胎儿期早期发育，在妊娠中期开始时达到形态成熟。TE3+皮质胸腺上皮最有可能源自内胚层第三咽囊，而A2B5/TE4+髓质和被膜下皮质胸腺上皮可能源自第三咽裂外胚层。胎儿肝脏和卵黄囊的CD7+、CD4-、CD8-、表面(s)CD3-T细胞前体在胎儿妊娠7至8周之间开始定殖于胸腺，随后发育中的胸腺细胞迅速表达其他T细胞谱系表面分子。CD7+、CD4-、CD8-、sCD3-胸腺细胞产生TCRαβ和TCRγδ谱系的T细胞。人类胸腺上皮细胞产生多种细胞因子，包括IL1、IL6、TGFα、白血病抑制因子(LIF)、M-CSF、G-CSF和GM-CSF，这些分子可能在胸腺细胞选择、激活和分化的多个阶段发挥重要作用。人类胸腺上皮未来研究的重要领域包括研究CD7+、CD4-、CD8-、sCD3-T细胞前体对TE细胞产生的细胞因子的淋巴样和非谱系分化潜能，研究胸腺微环境中细胞因子释放的触发信号，以及研究TCR-MHC介导的TE-胸腺细胞相互作用。
