PIROPLASMA 



195 



PLASTIDS 



shaped parasites of red blood cells caus- 

 ing diseases of great importance in 

 domestic and other animals but not as 

 yet found in man. They can be colored 

 by any good blood stain. Giemsa and 

 May-Giemsa are recommended. 



Pituitary. The microscopic techniques for 

 this conductor of the endocrine sym- 

 phony are obviously too numerous to 

 mention. Consult each issue of the 

 Quart. Cum. Index Med. 



To differentiate 2 classes of acido- 

 philes in the cat a modification of 

 Heidenhain's "azan" modification of 

 Mallory's connective tissue stain is 

 proposed by Dawson , A . B . and Fri edgood , 

 H. B., Stain Tech., 1938, 13, 17-21. T. 

 Maxwell, Jr. {ibid, 93-96) proposes a 

 modification especially designed for the 

 basophiles and Koneff, H. H. {ibid, 49- 

 52) one for the rat. In addition all 

 within the space of a few months, Lewis, 

 M. R., and Miller, C. H., Stain Techn., 

 193S, 13, 111-114 give following direc- 

 tions to demonstrate 2 types of granular 

 cells in the pars nervosa. Fix in 3% 

 aq. potassium bichromate 2 parts and 

 half sat. corrosive sublimate in 95% 

 ale. 1 part, 12-24 hrs. with 1 change. 

 Dehydrate to 70% alcohol to which add 

 few drops iodine. Change each day 

 until solution retains color. Dioxan, 

 8-24 hrs., 3 changes. Dioxan + little 

 paraffin. Paraffin 4 changes. Cut sec- 

 tions 4 microns and deparaffinize. Stain 

 0.25% aq. acid fuchsin 30 min. Then 

 1-24 hrs. in Mallory's stain (aq. dest., 

 100 cc; anilin blue, 0.5 gm.; orange G, 

 2 gm. and phosphotungstic acid, 1 gm.). 

 Differentiate in 95% alcohol until no 

 more color comes out. Abs. ale, xylol, 

 balsam. To identify microglia in neuro- 

 hypophj^sis see Vazquez -Lopez, E., J. 

 Anat., 1942, 76, 178-186. Differential 

 stain for mouse pituitary (Dickie, M. 

 M., Science, 1944, 100, 297-298). Pitui- 

 cytes by Hortega silver carbonate tech- 

 nique (Shanklin, W. M., Stain Techn., 

 1943, 18, 87-89). 



Placenta. Those proposing to investigate 

 the placenta would do well to consult 

 the most recent paper in a series dir- 

 ected by Dr. George B. Wislocki at 

 Harvard (Wislocki, G. B., Deane, H. W. 

 and Dempsey, E. W , Am. J. Anat., 

 1946, 78, 281-345). Many techniques, 

 mostly histochemical, have been 

 brought to bear on this organ in a well 

 developed, long term, program of re- 

 search and the results obtained thereby 

 are well illustrated, frequently by ex- 

 cellent colored figures. 



Plants. Except for pathogenic Bacteria 

 and Fungi, technique for plants does not 

 come within the scope of this book. 

 However much is to be learned, es- 

 pecially in microchemistry, from many 



methods employed by botanists and the 

 reader is advised to consult Johansen, 

 D. A. Plant Microtechnique. New 

 York: McGraw-Hill, 1940, 523 pp. 



Plasma Cells. Since plasma cells (of the 

 Marschalko type) are mainly identified 

 by recognition of a small area near the 

 nucleus which does not stain as intensely 

 as the rest of the cytoplasm with basic 

 dyes, it is important to use a technique 

 which reveals basophilia. In practice 

 Giemsa 's stain, or a good coloration with 

 hematoxjdin and eosin, is generally 

 sufficient. Unna used the term "plasma 

 cell" for almost any kind of cell with 

 much plasma including macrophages so 

 that the designation Unna's plasma cell 

 is almost meaningless. 



Plasma Membrane, see Cell Membranes. 



Plasma! Reaction, see SchiflF's Reaction. 



Plasmalogen. A component of the cyto- 

 plasm which gives a positive Feulgen 

 test (Bourne, p. 22). 



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, chemistry and physics of (Bartoe, 

 W. F., J. Tech. Meth., 1940, 20, 6-11). 

 In museum work (Kramer, F. M., J. 

 Tech. Meth., 1940, 20, 14-23). As sub- 

 stitute for cover glasses (Suntzeff, V. 

 and Smith, I., Science, 1941, 93, 158- 

 159; Russell, W. O., J. Tech. Meth., 

 1942, 22, 65-70). As mounting media 

 (Hutner, S. H., Stain Techn., 1941, 16, 

 177). As substitute for quartz for light 

 conduction (Williams, R. G., Anat. 

 Rec, 1941, 79, 263-270). As cover 

 glasses. DeAngelis, E., J. Lab. & 

 Clin. Med., 1945, 30, 469-471 recom- 

 mends 2, Acryloid B-77 and Vinylseal. 

 After preparation is stained and passed 

 through alcohols to xylol, dip it slowly 

 into plastic solution, allow to remain 

 30 sec. slowly lift out and drain oft' ex- 

 cess plastic by placing at an angle in a 

 rack. Repeat if thicker covering is de- 

 sired, covering can be made very hard 

 by baking in oven at 140°C. for 1 hr. 

 Many advantages and some disadvan- 

 tages are discussed by DeAngelis. 



Plastids are by definition simply formed 

 bodies. The term is usually applied to 

 certain cytoplasmic bodies in plants. 

 They may be colorless leucoplastids, 



