In human hepatocellular carcinoma cells the total membrane surface area of each major organelle is a particular allometric function of the cytoplasmic volume. A morphometric study.

Morphometric analysis by both light and electron microscopy was performed in cells from five cases of human, hepatocellular carcinoma (HCC) and in three control cases. In each case, three fragments were examined individually and the following morphometric parameters evaluated: a) nuclear, cytoplasmic and cell volumes; b) volume density and absolute volume of the rough ER, smooth ER, mitochondria, Golgi apparatus, peroxisomes, dense bodies and cytoplasmic matrix; c) surface density, surface/ volume ratio, and total surface area of rough ER, smooth ER and outer mitochondrial membranes. The parameters obtained from HCC cases showed ample scatter of data, all control values lying within the interval between the extreme values for the various parameters. Both the original and the logarithmically transformed data on volume and total membrane surface area of organelles (y) and of the cytoplasmic volume (x) were regressed using first degree regression equations. The original values for volume and total surface area of rough ER, total ER and mitochondria were linearly related to the corresponding values for cytoplasmic volume. The allometric analysis carried out with the logarithms also revealed significant regressions between cytoplasmic volume and smooth ER parameters not detectable when using the original x and y values. It showed, in addition, that in progressively larger cytoplasmic volumes, the cisternae of both rough and smooth ER tend to appear more compacted and a higher portion of the total ER membrane tends to be constituted of smooth ER. Within the wide range of variation in cytoplasmic volume of the HCC cells, the volume and total surface of the organelles do not vary randomly. These data indicate that in the small, normal-sized and large tumoral cells the mechanisms responsible for the cytoplasmic volume and for the corresponding total volume and membrane surface area of each major organelle are interdependent. Such an interdependence gives no support to ideas implying that the variation in size of cancer cells, an element of pleomorphism, would result of anarchical intracellular synthetic and/or degradative conditions.