The current study was intended to evaluate impacts of both iron (Fe) enrichment and overload (in the form of ferrous sulphate heptahydrate, FeSO₄.7H₂O) on ultrastructural characteristics of human adrenocarcinoma NCI-H295R cell line. Here, the NCI-H295R cells were treated with 0, 3.90, and 1000 µM FeSO₄0.7 H₂O, and consequently proceeded for purposes of ultrastructural studies. Micrographs taken under transmission electron microscope (TEM) were investigated from the qualitative and quantitative (unbiased stereological approaches) aspects, and obtained findings were compared among the three groups of the cells. The ultrastructural features related to the steroidogenic process were found to be similar between the untreated and both Fe-exposed cell populations, with conspicuous mitochondria with well-defined lamellar cristae (creating clusters of varying sizes in the regions of increased energy demands) and concentric whorls of smooth endoplasmic reticulum (SER) being the most noticeable characteristics. The precise estimates of the component (volume, surface) fractions of the nucleus, mitochondria, and lipid droplets (LDs), as well as of the nucleus/cytoplasm (N/C) ratio have revealed close similarities (P > 0.05) in all cell groups investigated. Nonetheless, the low concentration of FeSO₄.7H₂O exhibited beneficial action on ultrastructural organization of the NCI-H295R cells. In effect, these cells were distinguished by mitochondria with smoother surfaces and clearer outlines, higher density of thin, parallel lamellar cristae (deeply extending into the mitochondrial matrix), and more widespread distribution of fine SER tubules as compared to the control ones, all of them suggesting higher level of energy requirements and metabolic activity, and more intensive rate of steroidogenesis. Interestingly, no obvious ultrastructural modifications were observed in the NCI-H295R cells treated with high FeSO₄.7H₂O concentration. This finding can be linked to either an adaptive ultrastructural machinery of these cells to cope with the adverse effect of the element or to insufficient dose of FeSO₄0.7 H₂O (1000 µM) to induce ultrastructural signs of cytotoxicity. Purposefully, the results of the current study complement our previous paper dealing with impacts of FeSO₄.7H₂O on the NCI-H295R cell viability and steroidogenesis at the molecular level. Hence, they fill a knowledge gap considering structure-function coupling in this cellular model system upon the metal exposure. This integrated approach can enhance our understanding of the cellular responses to Fe enrichment and overload which can be helpful for individuals with reproductive health concerns.

_{当前的研究旨在评估铁 (Fe) 富集和过载（以七水硫酸亚铁 FeSO 4} .7H _{2 O}的形式）对人肾上腺癌 NCI-H295R 细胞系超微结构特征的影响。此处，NCI-H295R 细胞用 0、3.90 和 1000 µM FeSO ₄ 0.7 H ₂ O 处理，然后进行超微结构研究。从定性和定量（无偏见体视学方法）方面对透射电子显微镜（TEM）下拍摄的显微照片进行研究，并将获得的结果在三组细胞之间进行比较。发现未处理的细胞群和暴露于铁的细胞群之间与类固醇生成过程相关的超微结构特征相似，具有明显的线粒体和明确的层状嵴（在能量需求增加的区域形成不同大小的簇）和同心螺纹平滑内质网（SER）的特征是最显着的特征。对细胞核、线粒体和脂滴 (LD) 的组成（体积、表面）分数以及细胞核/细胞质 (N/C) 比率的精确估计显示，所有这些都具有密切的相似性 (P > 0.05)。细胞组进行了研究。尽管如此，低浓度的FeSO ₄ .7H ₂ O对NCI-H295R细胞的超微结构组织表现出有益的作用。实际上，与对照细胞相比，这些细胞的特点是线粒体具有更光滑的表面和更清晰的轮廓，更高密度的薄平行层状嵴（深入延伸到线粒体基质中），以及更广泛分布的细 SER 小管，所有这些它们表明更高水平的能量需求和代谢活动，以及更高水平的类固醇生成速率。_{有趣的是，在高浓度FeSO 4} .7H ₂ O处理的NCI-H295R细胞中没有观察到明显的超微结构改变。这一发现可能与这些细胞应对元素不利影响的适应性超微结构机制有关，也可能与 FeSO ₄ 0.7 H ₂ O (1000 µM) 剂量不足以诱导细胞毒性超微结构迹象有关。本研究的结果有目的地补充了我们之前的论文，该论文涉及 FeSO ₄ .7H ₂ O 在分子水平上对 NCI-H295R 细胞活力和类固醇生成的影响。因此，他们填补了考虑该细胞模型中的结构-功能耦合的知识空白金属暴露后的系统。这种综合方法可以增强我们对细胞对铁富集和超载反应的理解，这对有生殖健康问题的个体有帮助。