| pubmed-article:3066304 | pubmed:abstractText | The intrathymic distributions of facteur thymique sérique (FTS)-containing cells and Ia-expressing cells were examined by a double immunofluorescence technique in C57BL/6 mice of various ages. In the thymic medulla of all the mice examined, there were both FTS-immunoreactive cells and Ia-immunoreactive cells. The former cells, epithelial in nature, extended elongate cytoplasmic processes, while the latter were connected with each other by their spiny processes. The FTS-immunoreactive epithelial cells were all Ia-negative. The FTS-immunoreactive cells and Ia-immunoreactive cells were located in close proximity to each other. The cortex of the adult mice contained no FTS-immunoreactive epithelial cells. The cortex of the newborn and old mice, however, contained scattered FTS-immunoreactive epithelial cells with processes. FTS-immunoreactive cells in the cortex of the old mice possessed Ia-immunoreactive partner cells, while those in the cortex of newborn mice did not. In the marginal zone of the medulla of old mice, there were several cavities bounded by a partly ciliated epithelium and containing lymphocytes. The epithelial cells lining the cavities showed intense immunofluorescence for FTS. In addition to the epithelial cells, a certain population of round cells with thin cytoplasm lacking in discernible processes immunofluoresced for FTS. Located both in the medulla and in the cortex, these round cells were postulated to be thymocytes, the target cells of FTS, binding FTS on their cell surface. | lld:pubmed |
