Fang D, Dockery P, Weatherhead B
Department of Anatomy, University of Hong Kong, Hong Kong.
Pigment Cell Res. 1997 Feb-Apr;10(1-2):77-84. doi: 10.1111/j.1600-0749.1997.tb00471.x.
The relationship between melanosome size and number and melanin content has been investigated in Cloudman S91 melanoma cells growing in vitro using both "model-based" and "design-based" stereological procedures. Cells were cultured for 4 days, harvested at daily intervals, and resin-embedded for light and electron microscopy; one aliquot of each sample of cells was assayed to determine its melanin content. By comparing their volume-weighted mean nuclear volume and their number-weighted mean nuclear volume, we have found that the nuclei of Cloudman melanoma cells form a fairly homogeneous population. The volume fraction and absolute volume of premelanosomes (VVpm, cell and Vpm) and mature melanosomes (VVmm, cell and Vmm) were all found to decrease progressively throughout the period of culture as did the number of premelanosomes (Npm) and mature melanosomes (Nmm). Whilst the volume-weighted mean volume of individual stage I and stage II premelanosomes, (VVipm), remained fairly constant at about 10 nm3, the volume of individual stage III and IV mature melanosomes showed significant variation ranging between about 13 nm3 and 32 nm3. The melanin content of the cells decreased progressively over the 4 days of culture. There were, however, considerable variations in both the average melanin content per unit volume of mature melanosomes, in the range 170-600 fg/micron3, and in the melanin content per individual mature melanosome, in the range 3-12 fg. Our findings show that stereological techniques can provide unbiased and sensitive tools for the study of the morphological basis of melanogenesis; their value will become even more evident when they are combined with techniques for the localization of melanogenic enzymes and their substrates.
利用“基于模型”和“基于设计”的体视学方法，对体外培养的Cloudman S91黑色素瘤细胞中黑素小体的大小、数量与黑色素含量之间的关系进行了研究。细胞培养4天，每天定时收获，经树脂包埋后用于光学显微镜和电子显微镜观察；对每份细胞样品的一份等分试样进行分析，以确定其黑色素含量。通过比较它们的体积加权平均核体积和数量加权平均核体积，我们发现Cloudman黑色素瘤细胞的细胞核构成了一个相当均匀的群体。前黑素小体（VVpm, cell和Vpm）和成熟黑素小体（VVmm, cell和Vmm）的体积分数和绝对体积在整个培养期间均逐渐下降，前黑素小体（Npm）和成熟黑素小体（Nmm）的数量也是如此。虽然I期和II期单个前黑素小体的体积加权平均体积（VVipm）保持在约10 nm3相当恒定，但III期和IV期单个成熟黑素小体的体积显示出显著变化，范围在约13 nm3至32 nm3之间。细胞的黑色素含量在培养的4天中逐渐下降。然而，每单位体积成熟黑素小体的平均黑色素含量在170 - 600 fg/μm3范围内，以及每个成熟黑素小体的黑色素含量在3 - 12 fg范围内，均存在相当大的差异。我们的研究结果表明，体视学技术可为黑素生成的形态学基础研究提供无偏且灵敏的工具；当它们与黑素生成酶及其底物的定位技术相结合时，其价值将变得更加明显。
