CLEARING 



69 



COCHINEAL 



rectly from the fixative, Bouin or forma- 

 lin, without washing, to 3 changes of 

 pure dioxan within 4 hrs. and thence 

 into 3 chiinges of paraffin as advised by 

 Graupner, H. and Weissberger, A., 

 Zool. Anz., 1931, 96, 204-206. Stowell, 

 R. E., Stain Techn., 1941, 16, 67-83 

 confirms and extends earlier work of 

 Seki which shows that, although xylol 

 shrinks tissues more than dioxan, in 

 placing in hot paraffin, the final shrink- 

 age is greater in tissues after dioxan. 

 When great haste is necessary Mallory 

 (p. 54) suggests acetone \-2 hrs. ; benzol, 

 15-30 min. ; and paraffin 3 changes, 30-90 

 min. The shrinkage, however, is very 

 marked and it would probably be better 

 to use Frozen Sections. 



By the Altmann-Gersh technique, 

 which is at once very time consuming 

 and very valuable for special purposes, 

 fixation, alcoholic dehydration and clear- 

 ing can be side stepped and the dried 

 tissue directly impregnated with 

 paraffin. 



2. As the step following dehydration 

 of sections before mounting. The clear- 

 ing is of course easier and much quicker 

 owing to the thinness of the tissue. 

 Again xylol comes first and will probably 

 not be displaced though some prefer 

 toluol. It is not necessary to protect 

 against shrinkage and brittleness. 

 When desired, abs. ale. can be omitted 

 and the clearing be done from 90 or 

 even 80% ale. with terpineol, clove oil, 

 anilin oil, beechwood creosote, Bergamot 

 or some other substance. 



3. As a means of rendering clearly 

 visible certain structures in embryos or 

 whole tissues. Clearing is generally 

 done by the Spalteholz method. See 

 Cartilaginous Skeleton and Ossification 

 centers. When glycerin mixtures are 

 employed as Mounting Media they also 

 clear the tissues. See Groat, R. A., 

 Stain Techn., 1941, 16, 111-117 for clear- 

 ing tissues with mixtures of tributyl 

 and tri-o-cresyl phosphates. 



Cloudy Swelling. This is a marked swelling 

 and granulation of the cytoplasm of 

 cells. It is sometimes observed post- 

 mortem in acute febrile conditions 

 especially in the kidneys, liver and myo- 

 cardium. An almost meaningless syno- 

 nym, often used, is Parenchymatous 

 Degeneration. The extent of cloudy 

 swelling that may occur in vivo and 

 from which the cells may recover is 

 not known. The fatty droplets present 

 can be demonstrated in Sudan stained 

 frozen sections of formalin fixed mate- 

 rial. Special stains for Fibrin, Myo- 

 fibrils and Mitochondria may be de- 

 sirable. 



Coacervates (L. acervus, a cloud or swarm) 



are masses of particles clumped together 

 (but encased in a little water) by a 

 change in their electrical charge while 

 in colloidal suspension in water or 

 by dehydration with resultant loss 

 of loosely bound water. Hirsch (G. 

 C, Form und StofTwechsel der Gol- 

 gi-Korper. Protoplasma Monographs, 

 Berlin, 1939) has likened the Golgi 

 apparatus to a coacervate. See Bensley, 

 R. R., Anat. Rcc, 1937, G9, 341-353 for 

 critical consideration of suggestion that 

 mitochondria are coacervates. 



Coagulation. A phenomenon frequently 

 encountered in the case of blood and 

 lymph is of wide occurrence and is in- 

 fluenced by many factors. Small quan- 

 tities of many electrolytes cause coagu- 

 lation of colloids. Some ions are much 

 more powerful in this respect than 

 others and certain "protective col- 

 loids" such as gelatin protect colloidal 

 suspensions against coagulating action 

 of electrolytes. Peptization is dis- 

 integration of the coagulum into col- 

 loidal particles. Water is employed as 

 a peptizing agent in dissolving glue, 

 agar, and similar materials (Holmes, 

 H. N., Glasser's Medical Physics, 257- 

 263). 



Cobalt Nitrate Silver for Golgi Apparatus. 



Coccidia. These sporozoa include many 

 parasites of great importance not only 

 to physicians and veterinarians but also 

 to cytologists who are interested in 

 their intracellular behavior. Conse- 

 quently the volume by Becker, E. R., 

 Coccidia and Coccidiosis of domesti- 

 cated, game and laboratory animals 

 and of man. Ames: Collegiate Press, 

 Inc., 1934, 147 pp. will contain numerous 

 helpful leads on the coccidia of the 

 digestive tracts of vertebrates and in- 

 vertebrates. 



Coccinel Red is 1,5-diamylaminoanthra- 

 quinone, an oil soluble dye, recom- 

 mended by Lillie, R. D., Stain Techn., 

 1945, 20, 73-75 as a stain for fat which 

 it colors deep orange red. Make up 

 stock solution of 4.2% in absolute 

 (99%) isopropanol. Dilute this down 

 to 30 or 40% isopropanol v/ith water and 

 treat frozen sections of normal cat kid- 

 ney and human adrenal with resulting 

 solution for 10-20 min. This solution 

 is only usal^le for several hours. Coc- 

 cinel red is a good counterstain after 

 hematoxylin. 



Coccinine (CI, 120), an acid monoazo dye, 

 light fastness 3 to 4, which colors sec- 

 tions pale pink not equal to Biebrich 

 Scarlet (Emig, p. 31). 



Cochineal (CI, 1239). This crimson dye 

 was in use by the Aztecs before the 

 Spanish conquest. It is derived from 

 an insect which feeds on a cactus. So 



