CENTRIFUGATION 



59 



CENTROSOMES 



centrifuge, Oxford, Clarendon Press, 



1940, 478 pp. 



The centrifuge has long been of help 

 in the displacement of certain com- 

 ponents of cells (especially marine eggs) 

 in order to determine their functional 

 roles. It has also proved invaluable in 

 the investigation of cytoplasmic and 

 nuclear Viscosity, which see. 



In recent years centrifugation has 

 opened a new chapter in microchemistry 

 by the part which it has played in the 

 collection of cellular components in 

 sufficient volume for analysis. Pioneer 

 work was done with the liver. The 

 Bensleys (p. 6) give instructions which 

 are in part as follows. First perfuse the 

 abdominal organs of a guinea pig with 

 about 1000 cc. 0.85% aq. sodium chloride 

 (see Perfusion). This removes a good 

 deal of the blood. Excise liver and 

 grind up thoroughly in a mortar. Place 

 the resulting thick fluid in large centri- 

 fuge tubes, add about twice the volume of 

 0.85% aq. sodium chloride and balance 

 the tubes with more as may be necessary. 

 If complete separation of mitochondria is 

 desired centrifuge for 1 min. at 3000 

 r.p.m. which results in stratification. 

 In first and lowest stratum, at the bot- 

 tom of the tubes, will be found liver cells, 

 cell debris and connective tissue ele- 

 ments; in the second, nuclei and red 

 blood cells ; in the third mitochondria 

 and small cell fragments ; and in the 

 fourth and uppermost, free fatty drop- 

 lets. The materials in any of these 

 layers can then be collected by drawing 

 up in a pipette, suspended again in salt 

 solution and purified by further cen- 

 trifugation. 



For the isolation of ellipsin (structural 

 protein) and mitochondria see Bensley, 

 R. R. and Hoerr, N. L., Anat. Rec, 

 1934, 60, 251-266 and 449-455. Since it 

 is in the mitochondrial fraction resulting 

 from centrifugation tliat vitamin A is 

 found the Goerners have greatly ex- 

 tended the usefulness of the method in a 

 series of studies on tumors (Goerner) 

 A., J. Biol. Chem., 1937-38, 122, 529- 

 538 and A., and M. M., ihid, 1939, 128, 

 559-565). The technique has been 

 further improved by Claude (A., Sci- 

 ence, 1938, 87, 467-468 ; Cold Spring Har- 

 bor Symposia on Quantitative Biology 



1941, 9, 263-270) who used 18000 r.p.m. 

 See, particularly, standardized tech- 

 niques in his 1941 paper. Beams, 

 H. W. and King, R. L., Anat. Rec, 

 1940, 76, 95-101, and in a series of 

 other papers, have greatly contributed 

 to the use of ultracentrifugation in the 

 solution of biological problems. See 

 Lucas, A. M., Am. J. Path., 1940, 16, 

 739-760 on intranuclear inclusions. 



Centrifuge Microscope. By this ingenious 

 combination of microscope and cen- 

 trifuge it is possible to observe living 

 cells with the highest dry objectives 

 while they are actually being cen- 

 trifuged. Cells or organisms to be 

 examined are placed in isotonic media 

 of appropriate density in special slides 

 constructed so that the centrifugal 

 force derives them into approximately 

 the focus of the objective. The clear- 

 ness of the 2 dimensional image is not 

 conditioned by the speed of rotation. 

 The slide is fixed into the centrifuge 

 head remote from the axis of rotation. 

 Strong light is focussed by condensing 

 lens from above onto the slide . A prism 

 below the slide in the centrifuge head 

 directs the light toward the axis of 

 rotation directly through an objective. 

 When received at the axis of rotation it 

 is directed upward by reflecting prisms 

 into an ocular in position above the 

 center of the centrifuge head. Not only 

 can stages in displacement of intra- 

 cellular components be watched but 

 permanent records are easily made in 

 the form of motion pictures. Since its 

 introduction by Harvey and Loomis in 

 1930 several structural improvements 

 have been achieved. A commercial 

 design is made by Bausch and Lomb 

 Optical Company (Harvey, E. N., in 

 Glasser's Medical Physics 1944, 147). 



Centriole, see Centrosome. 



Centrosomes (G. Kentron, center; soma, 

 body), sometimes called a "central 

 body", is a minute spherule which is a 

 dynamic center of some sort involved in 

 cell division. It is sometimes called a 

 centriole though Conklin (Cowdry's 

 General Cytology, pp. 542 and 544) says 

 that a central body, the centriole, 

 appears within the centrosome during 

 mitosis. When the centrosome is double, 

 that is consists of two minute bodies 

 side by side, it is designated a diplosome. 

 About the centrosome, or diplosome, 

 there is usually a clear area which is 

 known as a cenlrosphere. The centro- 

 some, or centriole plus the clear area is 

 called the cytocentrum. For terminology 

 see Wilson, E. B., The Cell. New York : 

 Macmillan Co., 1925, 1232 pp. For 

 functional significance see Fry, H.J., 

 Biol. Bull., 1929, 57, 131^150. Giant 

 centrospheres in degenerating cells are 

 described by Lewis and Lewis (Cow- 

 dry's General Cytology, p. 427 )_ and 

 multiplication of centrioles in striated 

 muscle tumors by Wolbach, E. B., Anat. 

 Rec, 1928, 37, 255-273. 



Centrosomes are not easily demon- 

 strated in tissue sections. The tech- 

 nique originally used by Heidenhain 

 (Arch. f. mikr. Anat., 1894, 42, 665) ap- 

 pears to be the best. It consists of 



