ISOLATION AND COMPOSITION OF NUCLEI AND NUCLEOLI 



103 



Reservoir 



Barrel, ground 

 mside. Very 

 thick-walled 

 glass tubing - 



Large 



rubber 



stopper 



Uq 



MAPINE 

 BIOLOGICAL 



LABORATORY 



LIBRARY 



•Plunger, of f ViOODS HOLE, W^ASS. 



glass rod \ ,^_ ^^ Q^ 1^ 



Ball 



Fig. 2. Ground-glass homogenizer, 0.25 times actual size. Construction probably 

 could also be in stainless steel, particularly if larger sizes were to be made. 



inder is occupied entirely by a circle of liquid, so that the forces in the 

 Uquid are not too great to be overcome when the plunger is moved. If a 

 homogenizer of the Hagan-Potter-Elvehjem type were constructed with an 

 equally good fit, it would behave hke a hypodermic syringe, in that the 

 plunger could not be driven through the liquid in the cylinder. 



Other advantages of the new homogenizer are that the friction is reduced 

 to a minimum so that no appreciable heating can occur, and no ground glass 

 accumulates. The relatively tight fit makes it possible to break a very high 

 percentage of the cells present, and yet the nuclei are only slightly damaged. 

 Mitochondria may not be damaged to a detectable extent. 



A hand-homogenizer which might resemble the one just described has 

 been mentioned in the literature,-^ but the description of this instrument is 

 so meager that it is impossible to know whether it is similar or not. Wilbur 

 and Skeen^^ have described a hand-operated homogenizer with a pestle made 

 of a glass rod, the lower end of which is covered with a piece of tapered 

 gum rubber tubing. 



c. Perfusion of Organs for the Removal of Blood 



A topic which deserves some consideration in a description of methods for 

 isolating cell nuclei is the perfusion of organs to remove blood. If the most 



2» H. Stern, V.G. Allfrey, A. E. Mirsky, andH.Saetren, /. Gen. Physiol. 35,559 (1952). 

 2^ K. M. Wilbur and M. V. Skeen, Science 111, 304 (1950). 



