Melanomacrophagic centers (MMCs) were studied in the liver of zebrafish using transmission electron microscope (TEM). The MMCs were located in the space of Disse (SD), and their pseudopodia protruded into the lumen of sinusoids. The degree of extension of body structure of MMCs in the SD was determined by the size of the phagocytosed content. An irregular or amoeboid nucleus was present. Vacuoles were occasionally present, both, in endothelium and MMCs. The cytoplasm of MMCs showed several engulfed structures. The most common structure was the presence of mitochondria of small to giant size and distorted shape with inconspicuous cristae. The product of mitochondrial degeneration accompanied by lysosomes contributed to the formation of lipofuscins. Besides, changes were also observed in rough endoplasmic reticulum (rER), the Golgi complex, and lysosomes. Occasionally, small to large fragments of the erythrocytes were found in the cytoplasm of MMCs. The rER encompassed the mitochondria and lipid droplets forming a membrane-like structure. Golgi complex were dilated. Lysosomes fused with such membrane-bound structures contributed to the formation of the lipofuscin. The results provide evidence of the role of liver-resident MMCs of zebrafish in phagocytosis of damaged organelles, clearance of the worn-out erythrocytes, and lipofuscin formation.

中文翻译：

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斑马鱼肝脏中黑色素吞噬中心和脂褐素的超微结构证据。

使用透射电子显微镜（TEM）在斑马鱼的肝脏中研究了黑色素吞噬中心（MMC）。MMC位于Disse（SD）的空间中，其伪足突入正弦管腔中。SD中MMC的身体结构扩展程度取决于吞噬内容物的大小。存在不规则或变形虫细胞核。内皮和MMC中均偶尔存在液泡。MMC的细胞质显示出几个被吞噬的结构。最常见的结构是线粒体的大小从小到大，形状扭曲且ista缝不明显。线粒体变性伴随溶酶体的产物有助于脂褐素的形成。此外，高尔基体，粗面内质网（rER）也观察到了变化，和溶酶体。有时，在MMC的细胞质中会发现小到大的红细胞碎片。rER包含线粒体和脂质小滴，形成膜状结构。高尔基体扩张。融合有这种膜结合结构的溶酶体有助于脂褐素的形成。结果提供了斑马鱼的肝脏驻留MMCs在吞噬受损细胞器，清除陈旧的红细胞和脂褐素形成中的作用的证据。