Ermak T H, Steger H J, Strober S, Owen R L
Department of Medicine, University of California, San Francisco.
Am J Pathol. 1989 Mar;134(3):529-37.
The cytoarchitecture of Peyer's patches that were depleted of their lymphocytes by total lymphoid irradiation (TLI) was examined with particular attention to the effects on M cells in the follicle epithelium and on mononuclear cells in follicle domes underlying the epithelium. Five-month-old, specific pathogen-free Balb/c mice were irradiated with 200-250 rad/day, five times a week to a total dose of 3400-4250, and their Peyer's patches were either fixed for electron microscopy or frozen for immunohistochemistry 1-4 days after completion of irradiation. Control mice were examined at the same time intervals. Follicle domes of TLI mice had approximately one fourth the epithelial surface area of domes of control mice. Within the epithelium, lymphoid cells were virtually depleted after TLI, and yet the epithelium contained M cells. In control mice, most M cells were accompanied by lymphoid cells in invaginations of the apical-lateral cell membrane. In TLI mice, most M cells did not have such apical-lateral invaginations and were columnar shaped. Other than lacking lymphocytes, these cells appeared to be mature M cells. Some M cells did have lymphoid cells or granular mononuclear cells below their basal membranes, adjacent to the basal lamina. Below the epithelium, the proportion of granular mononuclear cells was greatly increased following TLI. The retention of M cells and the increase in proportion of granular mononuclear cells in follicle domes are consistent with selective depletion of lymphocytes following TLI. Persistence of M cells without lymphocytic invaginations after TLI suggests that M cells can differentiate in the absence of, or at least in the presence of very few, lymphocytes, and that invagination by lymphocytes is not necessary to maintain mature M cell morphology.
通过全淋巴照射（TLI）去除淋巴细胞的派尔集合淋巴结的细胞结构被进行了检查，特别关注其对滤泡上皮中的M细胞以及上皮下方滤泡圆顶中的单核细胞的影响。对5月龄的无特定病原体的Balb/c小鼠，以每天200 - 250拉德的剂量、每周5次进行照射，总剂量达3400 - 4250拉德，在照射完成后1 - 4天，将它们的派尔集合淋巴结要么固定用于电子显微镜检查，要么冷冻用于免疫组织化学检查。同时对对照小鼠进行相同时间间隔的检查。TLI小鼠的滤泡圆顶的上皮表面积约为对照小鼠圆顶的四分之一。在上皮内，TLI后淋巴细胞几乎被耗尽，但上皮中仍含有M细胞。在对照小鼠中，大多数M细胞在顶端 - 侧面细胞膜的内陷处伴有淋巴细胞。在TLI小鼠中，大多数M细胞没有这种顶端 - 侧面内陷，呈柱状。除了缺乏淋巴细胞外，这些细胞似乎是成熟的M细胞。一些M细胞在其基底膜下方、紧邻基膜处确实有淋巴细胞或颗粒状单核细胞。在TLI后，上皮下方颗粒状单核细胞的比例大幅增加。滤泡圆顶中M细胞的保留以及颗粒状单核细胞比例的增加与TLI后淋巴细胞的选择性耗竭一致。TLI后没有淋巴细胞内陷的M细胞的持续存在表明，M细胞可以在没有淋巴细胞的情况下分化，或者至少在淋巴细胞极少的情况下分化，并且淋巴细胞的内陷对于维持成熟M细胞的形态不是必需的。
