PLANT CELL WALLS 



273 



PLASMA MEMBRANE 



hormone, even after repeated trans- 

 plantation (Jones, G. E. S., Gey, G. O. 

 and Gey, M. K., 1943, Bull. J. H. Hosp., 

 72, 26-38). 



The placentas of various mammals 

 other than man have been investigated 

 by multiple cytological and histochemi- 

 cal methods, for example, pig's placenta 

 (Wislocki, G. B. and Dempsev, E. W., 

 Am. J. Anat., 1946, 78, 181-225), cat's 

 placenta (Wislocki, G. B. and Dempsey, 

 E. W., Am. J. Anat., 1946, 78, 1-45), 

 rodent's placenta (VVislocki, G. B., 

 Dempsey, E. W. and Deane, H. W., 

 Am. J. Anat., 1946, 78, 281-345), shrew's 

 placenta (Blarina brevicauda and Sore.x 

 fumeus) (Wislocki, G. B. and Wirasatt, 

 W. A., Am. J. Anat., 1947, 81, 269-307), 

 and bat's placenta (Myotis lucifugus 

 lucifugus) (Wimsatt, W. A., Am. J. 

 Anat., 1949, 84, 63-141). The distribu- 

 tion of acid and alkaline phosphatases 

 in the placentas of pig, cat, rodents and 

 man has been the subject of a separate 

 report (Dempsey, E. W. and Wislocki, 

 G. B., Am. J. Anat., 1947, 80, 1-33). 

 By his method for lipase, Gomori (Men- 

 struation and its Disorders, edited by 

 E. T. Engle, 1950, C. C. Thomas) 

 depicts lipase activity in the allantoic 

 and vitelline placentas of mouse and 

 rat. The distribution of saliva-insolu- 

 ble glycoproteins, stained y)y the peri- 

 odic acid-Schiff procedure, is briefly 

 described in the placentas of pig, cat, 

 mouse, rat and man (Wislocki, G. B., 

 J. Natl. Cancer Inst., 1950, 10, 1341). 



Goldmann (Beitrage z. klin. Chir., 

 1909, 64, 192-265), in his classic account 

 of vital staining, described the intra- 

 vitam deposition of pyrrhol blue in 

 the placenta of the mouse. Wislocki 

 (Carnegie Contrib. to Embryol., 1920, 

 11, 45-60 and 1921, 13, 89-lOi), by em- 

 ploying the technique of vital staining, 

 demonstrated the storage of trypan 

 blue in the trophoblast of the placentas 

 of cats, rabbits and guinea pigs, while 

 Gerard (Arch. d. biol., 1925, 35, 269- 

 293) and Everett (J. Exp. Zool., 1933, 

 70, 243-284) carried out further similar 

 experiments in mice and rats. 



By using solutions of iron ammonium 

 citrate and sodium ferrocyanide which 

 could be traced in the placenta by 

 converting them into the Prussian 

 blue reaction, Cunningham (Am. J. 

 Physiol., 1920, 53, 439-456 and 1922, 

 60, 448-460; Proc. Soc. Exper. Biol, and 

 Med., 1923, 20, 343-345) investigated 

 the relative permeabilities of the 

 placentas of cats and rabbits to these 

 two substances. 



Everett (J. Exp. Zool., 1935, 70, 243- 

 280) has made a series of important 

 observations concerning the activities 



of the yolk-sac epithelium in the rat 

 by devising a technique for perfusing 

 the uterine circulation with thionin, 

 toluidin blue, methylene blue, brilliant 

 blue, Nile blue sulfate, Janus green, 

 neutral red and trypan blue. This 

 important study included direct micro- 

 scopic observation of the vitelline 

 epithelium in hanging drops in a con- 

 stant temperature chamber. 



An ingenious technique of tying off 

 the vitelline blood vessels in living 

 rabbit fetuses in utero, for the purpose 

 of ascertaining the route followed by 

 antibodies in their passage across the 

 placental barrier, has been devised 

 bv Brambell, Hemmings and Rowlands 

 (Proc. Roy. Soc, London, B, 1949, 136, 

 131-144). 



Transplantation of living fertilized 

 eggs and pieces of placenta, for purposes 

 of observing their growth, has also been 

 successfully carried out. Fertilized 

 mouse eggs, introduced into the ante- 

 rior chamber of the ej'e, into the ova- 

 rian bursa, or under the capsule of the 

 kidney, undergo development, produc- 

 ing large amounts of seemingly normal 

 placental trophoblast (Runner, M. N., 

 Anat. Rec, 1947, 98, 1-18; Fawcett, 

 D. W., Wislocki, G. B. and Waldo, C. 

 M., 1947, Am. J. Anat., 81, 413-444; 

 Fawcett, Anat. Rec, 1950, 108, 71-91). 

 Implants of trophoblast from 9-11 

 days of development also establish 

 themselves in the eye, although their 

 capacity for growth declines in relation- 

 ship to their age at the time of implanta- 

 tion (Grobstein, C, J. Exp. Zool., 

 1950, 114, 359-373). 



Plant Cell Walls, see Polysaccharides. 



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., also 

 McClung, 1950. 



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 imjx)rtant to use a technique 

 which reveals basophilia. In practice 

 Giemsa's stain, or a good coloration with 

 hematoxylin and eosin, is generally 

 sufficient. Unna used the term "plasma 

 cell" for almost any kind of cell with 

 much plasma incluaing macrophages so 

 that the designation Unna's plasma cell 

 is almost meaningless. 



Plasma Membrane, see Cell Membranes. 



