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 perfor med in cells from five cases of human, hepatocellular carcinoma (HCC) and in three control cases. In each case, three fragments were examine d 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, per oxisomes, dense bodies and cytoplasmic matrix; c) surface density, sur face/volume ratio, and total surface area of rough ER, smooth ER and o uter mitochondrial membranes. The parameters obtained from HCC cases s howed ample scatter of data, all control values lying within the inter val between the extreme values for the various parameters. Both the or iginal and the logarithmically transformed data on volume and total me mbrane 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 mi tochondria were linearly related to the corresponding values for cytop lasmic 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 v alues. It showed, in addition, that in progressively larger cytoplasmi c volumes, the cisternae of both rough and smooth ER tend to appear mo te compacted and a higher portion of the total ER membrane tends to be constituted of smooth ER Within the wide range of variation in cytopl asmic volume of the HCC cells, the volume and total surface of the org anelles do not vary randomly. These data indicate that in the small, n ormal-sized and large tumoral cells the mechanisms responsible for the cytoplasmic volume and for the corresponding total volume and membran e surface area of each major organelle are interdependent. Such an int erdependence gives no support to ideas implying that the variation in size of cancer cells, an element of pleomorphism, would result of anar chical intracellular synthetic and/or degradative conditions.