Leceta J, Garrido E, Torroba M, Zapata A G
Departamento de Biologia Celular, Facultad de Ciencias Biologicas, Universidad Complutense, Madrid, Spain.
Cell Tissue Res. 1989 Apr;256(1):213-9. doi: 10.1007/BF00224736.
Changes in the ultrastructure of the thymus of the turtle Mauremys caspica, with special reference to its non-lymphoid components, were studied in relation to the seasonal cycle. The thymic cortex contains framework-forming epithelial-reticular cells and free macrophages, while the medulla includes, in addition, mature and presumptive pro-interdigitating cells. The ultrastructural features of these cells are generally similar to those described for non-lymphoid components of the mammalian thymus. The turtle thymus undergoes cortical involution in spring, with recovery periods in May-June and during autumn. A moderate involution occurs in winter. At the beginning of spring, cortical (but not medullary) epithelial-reticular cells show degenerative changes, probably related to high levels of circulating testosterone. In spring and autumn, mature interdigitating cells are absent, but macrophages, monocytes, and pro-interdigitating cells are found. During May-June, the cortical epithelial-reticular population recovers and macrophages, monocytes, and interdigitating cells are actively phagocytic. In summer, the epithelial-reticular cells in both cortex and medulla display normal ultrastructural features; mature and immature interdigitating cells are absent and some macrophages are detected occasionally. The results suggest that non-lymphoid components of the reptilian thymus can play a role in governing T-lymphocyte differentiation, and that the thymic cortex and medulla exhibit different cycles of seasonal activity.
研究了地中海池龟胸腺超微结构的变化，特别关注其非淋巴细胞成分与季节周期的关系。胸腺皮质包含构成框架的上皮网状细胞和游离巨噬细胞，而髓质除此之外还包括成熟的和假定的前指状细胞。这些细胞的超微结构特征通常与哺乳动物胸腺非淋巴细胞成分所描述的特征相似。龟胸腺在春季经历皮质退化，在5月至6月以及秋季有恢复期。冬季发生中度退化。在春季开始时，皮质（而非髓质）上皮网状细胞出现退行性变化，可能与循环睾酮水平升高有关。在春季和秋季，成熟指状细胞不存在，但可发现巨噬细胞、单核细胞和前指状细胞。在5月至6月期间，皮质上皮网状细胞群体恢复，巨噬细胞、单核细胞和指状细胞具有活跃的吞噬作用。在夏季，皮质和髓质中的上皮网状细胞呈现正常的超微结构特征；成熟和未成熟的指状细胞不存在，偶尔可检测到一些巨噬细胞。结果表明，爬行动物胸腺的非淋巴细胞成分可能在调节T淋巴细胞分化中发挥作用，并且胸腺皮质和髓质表现出不同的季节性活动周期。
