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The World of Protozoa, Rotifera, Nematoda and Oligochaeta

Ref ID : 4304

Jytte Reichstein Nilsson; On the Correlation of the Volume of a Prolate-Spheroidal Cell, Tetrahymena, as Determined by Electronic Particle Counters and by Morphometry. J.Protozool. 37(6):500-504, 1990

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The cell volume provided by electronic particle counters may be incorrect. As a particle, or cell, passes the counting device, its volume is calculated as a sphere. The electronically derived, mean cell volume (electronic MCV) of a population of Tetrahymena (prolate spheroid) is smaller than the volume (morphometric MCV) calculated from measured cell length and width. This discrepancy was studied using a Coulter Multisizer particle counter and cell morphometry. The electronic MCV averaged 0.70 of the morphometric MCV (1.00) but changed from 0.72 (fast growth) to 0.63 and 0.76 (slow or no growth) for cells having a mean length/width of 2.05, 2.33 and 1.61, respectively. The measured diameter of latex particles (used for calibration) was identical to that stated, but the diameter of the electronic MCV was larger than the width of the cells which related to whether the length/width of the cells was above, or below, 2.00. Hence, electron particle counters register primarily the width of a prolate-spheroidal cell, oriented with its long axis in the direction of flow, and used this value as diameter for the calculated sphere, whereas for more spherical cells, tumbling without any orientation, a mean of the axes is used. Factors for correction of the electronic MCV of Tetrahymena are provided.