Castillo A, López-Fierro P, Zapata A, Villena A, Razquin B
Departamento de Biología Celular y Anatomía, Facultad de Biología, Universidad de León, Spain.
Am J Anat. 1991 Mar;190(3):299-307. doi: 10.1002/aja.1001900310.
This study reports the ultrastructure of subpopulations of epithelial cells of the thymic parenchyma during the post-hatching development of the rainbow trout, Salmo gairdner, kept at 14 degrees C. At hatching, the thymus contained a small number of medium and large thymocytes interspersed among three different types of epithelial cells: (1) epithelial cells adjacent to the connective tissue capsule; (2) ramified dark epithelial cells with electron-dense cytoplasm; and (3) pale electron-lucent epithelial cells displaying secretory-like features. All these cells types were anchored to one another by desmosomes and had apparently differentiated from the pharyngeal epithelium. At 4 days after hatching, the thymus enlarged, and numerous gaps occurred between the cell processes of contiguous epithelial cells adjacent to the capsular connective tissue. In 21-day-old trout, thymic trabeculae developed carrying blood vessels, and a subcapsular zone became evident containing lymphoblasts and large subcapsular epithelial cells. In 30-day-old trout, an outer thymic zone developed consisting of spindle-shaped epithelial cells which formed a dense network. At this stage, scattered cystic cells, which apparently differentiated from the pale epithelial cells, were present.
本研究报告了虹鳟（Salmo gairdner）在14摄氏度环境下孵化后发育过程中胸腺实质上皮细胞亚群的超微结构。孵化时，胸腺含有少量中型和大型胸腺细胞，散布于三种不同类型的上皮细胞之间：（1）与结缔组织被膜相邻的上皮细胞；（2）具有电子致密细胞质的分支状深色上皮细胞；（3）显示出类似分泌特征的浅色电子透明上皮细胞。所有这些细胞类型通过桥粒相互连接，并且显然是从咽上皮分化而来。孵化后4天，胸腺增大，与被膜结缔组织相邻的连续上皮细胞的细胞突起之间出现许多间隙。在21日龄的虹鳟中，胸腺小梁发育并带有血管，一个包含淋巴母细胞和大型被膜下上皮细胞的被膜下区变得明显。在30日龄的虹鳟中，一个由纺锤形上皮细胞组成的致密网络形成了胸腺外层区域。在此阶段，存在明显从浅色上皮细胞分化而来的散在的囊状细胞。
