Histology and ultrastructure of the thymus during development in tilapia, Oreochromis niloticus
Histology and ultrastructure of the thymus during development in tilapia, Oreochromis niloticus
复制标题
罗非鱼 Oreochromis niloticus 发育过程中胸腺的组织学和超微结构
DOI：
10.1111/joa.12597
复制
发表时间：
2017-05-01
影响因子：
2.4
通讯作者：
Wang, Miao
中科院分区：
文献类型：
--
作者：
Cao, Jianmeng;Chen, Qiong;Wang, Miao
硬骨鱼类的胸腺在产生功能性 T 淋巴细胞方面发挥着重要作用。然而，罗非鱼的胸腺尚不清楚，这极大地阻碍了对水生病原体感染罗非鱼免疫反应的研究。采用整体原位杂交（WISH）、光学和透射电子显微镜（TEM）系统研究了尼罗罗非鱼胸腺的组织学结构和超微结构，包括不同发育阶段的胚胎和幼鱼、幼鱼和成鱼。在受精后2天（dpf）的胚胎中，当水温为27℃时，首先用胸腺标记基因重组激活基因1（Rag1）标记胸腺原基的位置。在4-dpf胚胎中很容易观察到明显的胸腺结构。在这个阶段，胸腺充满了干细胞。 6dpf时，胸腺分化为皮质和髓质。胸腺的形状在4至10dpf的早期阶段呈蚕豆状，在20dpf的鱼幼虫中胸腺形状变为楔形。受精后6个月（mpf），胸腺分化为外围区、中心区和内部区。在此阶段，胸腺变性后，肌样细胞和脂肪细胞出现在内部区域。然后，到受精后一年（ypf），胸腺表现出更严重的退化，并且在此阶段没有观察到皮质和髓质的分离。在整个发育过程中，胸腺小梁和小叶均不存在。然而，典型的哈索尔小体仍然存在并经历了退化。此外，TEM显示胸腺组织含有多种细胞类型，即淋巴细胞、巨噬细胞、上皮细胞、成纤维细胞和肥大细胞。
The thymus in teleost fishes plays an important role in producing functionally competent T-lymphocytes. However, the thymus in tilapia is not well known, which greatly hampers investigations into the immune responses of tilapia infected by aquatic pathogens. The histological structure and ultrastructure of the thymus in Oreochromis niloticus, including embryos and larvae at different developmental stages, juveniles, and adult fish, were systematically investigated using whole mount insitu hybridization (WISH), and light and transmission electron microscopy (TEM). The position of the thymus primordium was first labeled in the embryo at 2days post-fertilization (dpf) with the thymus marker gene recombination activating gene 1 (Rag1), when the water temperature was 27 degrees C. Obvious structures of the thymus were easily observed in 4-dpf embryos. At this stage, the thymus was filled with stem cells. At 6dpf, the thymus differentiated into the cortex and medulla. The shape of the thymus was broad bean'-like during the early stages from 4 to 10dpf, and became wedge-shaped in fish larvae at 20dpf. At 6months post-fertilization (mpf), the thymus differentiated into the peripheral zone, central zone, and inner zone. During this stage, myoid cells and adipocytes appeared in the inner zone following thymus degeneration. Then, the thymus displayed more advanced degeneration by 1year post-fertilization (ypf), and the separation of cortex and medulla was not observed at this stage. The thymic trabecula and lobule were absent during the entire course of development. However, the typical Hassall's corpuscle was present and underwent degeneration. Additionally, TEM showed that the thymic tissues contained a wide variety of cell types, namely lymphocytes, macrophages, epithelial cells, fibroblasts, and mastocytes.