Laboratory of Histology and Embryology, Institute of Biomedical Sciences Abel Salazar (ICBAS), University of Porto (UPorto), Porto, Portugal.
Microsc Res Tech. 2010 Aug;73(8):766-78. doi: 10.1002/jemt.20820.
Sex differences exist in fish hepatocytes, but studies for characterizing their cytology throughout the breeding cycle are still scarce; suggesting changes, but most lacking quantitative data. To address this limitation, to complement baseline data generated from the brown trout model, and to prove that sex-specific seasonal changes exist, we made an unbiased stereological evaluation of the hepatocytic cytoplasm. Unprecedentedly for fish liver, the stereological design was exempt from model (biased) assumptions. Five (3 years old) animals per sex were studied in endogenous vitellogenesis, exogenous vitellogenesis, and spawning season end. Liver pieces for analysis were systematically sampled. Stereology was done in transmission electron microscopy (TEM) micrographs. Primary data generated relative volume estimates of the major cytoplasmic components. Such values were used for deriving absolute volumes (per cell and per liver). Lipid droplets did not show changes. As to other targets, trends at cell and liver levels were not always equal. If the hepatocyte was the reference space, the contents in mitochondria, dense bodies, glycogen, and cytosol changed seasonally, in both sexes. If taking the liver as the reference, changes attained the Golgi apparatus and rough endoplasmic reticulum (RER), besides dense bodies, glycogen (in females), and cytosol. The components volumes (namely per liver) were often positively (negatively for glycogen) correlated with the ovary weight, disclosing new associations and implications in fish. While also offering gold-standard data for backing morphofunctional correlations and pathology, we revealed a new process by which females increase the amount of RER and Golgi throughout vitellogenesis, breaking from the idea on how this event happens in fish.
鱼类肝细胞存在性别差异，但对整个繁殖周期中其细胞学特征的研究仍然很少；这些研究提示存在变化，但大多数缺乏定量数据。为了解决这一局限性，补充棕鳟模型产生的基线数据，并证明存在性别特异性的季节性变化，我们对肝细胞质进行了无偏立体学评估。前所未有地对鱼类肝脏进行了研究，该立体学设计免除了模型（有偏差的）假设。在内源性卵黄发生、外源性卵黄发生和产卵季节末期，每个性别各研究了 5 只（3 岁）动物。用于分析的肝组织块进行了系统采样。立体学是在透射电子显微镜 (TEM) 显微照片中进行的。主要数据生成了主要细胞质成分的相对体积估计值。这些值用于推导绝对体积（每个细胞和每个肝脏）。脂滴没有变化。至于其他靶标，细胞和肝脏水平的趋势并不总是相同的。如果肝细胞是参考空间，那么线粒体、致密体、糖原和细胞质中的内容物在两性中都会随季节变化。如果以肝脏为参考，除了致密体、糖原（在雌性中）和细胞质外，高尔基体和粗面内质网 (RER) 也会发生变化。成分体积（即每肝）通常与卵巢重量呈正相关（糖原呈负相关），揭示了鱼类中一些新的关联和影响。虽然为支持形态功能相关性和病理学提供了黄金标准数据，但我们还揭示了一个新的过程，即雌性在卵黄发生过程中如何增加 RER 和高尔基体的数量，这打破了人们对鱼类中这一事件发生方式的看法。
