PLASMA STAINS 



274 



PLASTICS 



Plasma Stains are too numerous to cata- 

 logue here. Lillie (p. 66-68) states 

 that they functionally are divisible 

 into two groups: plasma stains proper 

 and those selective for extracellular 

 materials such as collagenic and elastic 

 fibers, bone and cartilage matrix and 

 so on. 



Plasma Reaction, see Aldehydes and SchifT 

 Reaction. 



Plasmalogen. A component of the cyto- 

 plasm which gives a positive Feulgen 

 test (Bourne, p. 22). See Aldehydes. 



Plasmodesmata, dehydrogenase activity 

 in, see Triphenyltetrazolium Chloride. 



Plasmosin, the gel and fiber forming con- 

 stituent of the hepatic cell. Method of 

 isolation and properties (Bensley, R. R., 

 Anat. Rec, 1938, 72, 351-369). 



Plasmosome. The true nucleolus staining 

 with "plasma" or "acid" dyes, that is 

 to say, red with eosin in the hematoxylin 

 and eosin combination. The plasmo- 

 some apparently does not make any 

 direct contribution to chromosome for- 

 mation. Acidophilic nucleoli are quite 

 different from certain cytoplasmic gran- 

 ules which Arnold called "plasmo- 

 somes" and mitochondria termed "plas- 

 tosomes" by Meves. 



Plastics — Written by M. S. Lucas, Dept. 

 Biological Science, Michigan State 

 College, East Lansing. August 10, 

 1951 — Acrylic plastics have been de- 

 scribed very early for use as embedding 

 media in biological fields whereas poly- 

 ester resin plastics, the so-called "cold- 

 setting" plastics, have more recently 

 come into use. Acrylics require very 

 careful handling and the fumes are more 

 toxic than those of the polyester resins. 

 These features have somewhat deterred 

 the general use of acrylics. Finished 

 blocks of both types of plastic are clear 

 and resistant to damage; acrylics are 

 a little clearer but the difference is so 

 slight that it is not noticeable except 

 when a block of acrylic plastic is com- 

 pared directly with a block of polyester 

 resin. The plastics can be tinted or 

 even rendered opaque on the back by 

 addition of dyes and chemicals. The 

 specimens to be embedded can be 

 opaque or cleared. 



Techniques involved in successful 

 embedding of biological and medical 

 specimens are not difficult. However, 

 use of plastics is not as simple as some 

 pamphlets indicate. It is as precise a 

 technique as any used in histology and 

 for this reason many people have 

 mediocre success. Most successful 

 users of plastics feel that the possible 

 uses for them have only begun to be 

 described. It is a good idea for those 

 interested, to secure current pamphlets 



concerning new methods and also about 

 the development of new and simpler- 

 to-use plastics from the several firms 

 listed below as well as others not listed 

 here. 

 Acrylics 



1. The Polychemicals Dept., E. I. du 

 Pont de Nemours and Co., Wilming- 

 ton, Del. "Du Pont Plastics in 

 Medicine and Surgery", Mimeo. 

 Pp. 9, references. 



2. The Plastics Dept., Rohm and Haas 

 Co., Washington Sq., Phila. 5, Pa. 

 "Embedding Biological Specimens 

 in Acrylic Plastic", Mimeo. Pp. 6, 

 references. 



3. Description of and Methods for 

 Acrylics in general: "Preservation 

 of Agricultural Specimens in Plas- 

 tics". Miscell. Pub. No. 679 

 U.S.D.A., G. R. Fessenden, 1949. 

 Pp. 78, 111., Lit. Cited, bibliography. 



Polyester Resin Plastics. 



Selectron No. 5026, manufactured by 

 the Pittsburgh Plate Glass Co. The 

 following are some trade names under 

 which it is retailed. 



1. "Bio-plastic" — Wards Natural Sci- 

 ence Establishment, Inc., 3000 Ridge 

 Rd., E., Rochester 9, N. Y. "How 

 to Embed in Bio-plastic", 1950, 

 Pp. 20, 25^, references, 111. "Nat- 

 ural Science Bulletin" Published 

 monthly. 



2. "Castolite"— The Castolite Co., 

 Woodstock, 111. "Preserving Speci- 

 mens in Castolite", 1950, Mimeo. 

 Pp. 23, references. Instruction Man- 

 ual. 



3. "Turtox Embedding Plastic"— The 

 General Biological Supply House, 

 761 E. 69th PL, Chicago, ill. "Em- 

 bedding Specimens in Transparent 

 Plastic", Turtox Service Leaflet No. 

 33, 1951. 



4. "Carolina Embedding Plastic" — 

 Carolina Biological Co., Elon Col- 

 lege, N. Carolina. Instruction Book- 

 let 50?f. 



The pamphlets listed above contain 

 detailed procedures. They also give 

 the history and specifications of the 

 plastic and indicate biological materials 

 that are suitable for embedding. Most 

 of them contain large bibliographies. 

 In addition to the references listed in 

 these pamphlets, certain additional 

 work, can be mentioned. 



Albert Jehle (University Museum, 

 Univ. of Pennsylvania, Phila., Pa.) is 

 using dental acrylics as reconstruction 

 material in restoration of skeletons 

 (report in preparation). In some in- 

 stances he has replaced an entire bone 

 by preparing a plastic cast. 



A new technique for light and electron 



