MOLYBDENUM 



158 



MOUNTING MEDIA 



Molybdenum, see Atomic Weights. 



Mono-Azo Dyes. Amarnth, azo fuchsin, 

 benzene-azo-a-naphthylamine, bordeaux 

 red, brilliant yellow S, chromotrope 2R, 

 chrysoidin Y, fast yellow, janus green 

 B, metanil yellow, methyl orange, 

 methyl red, uarcein, nitrazine, oil red 

 O, orange G, orange I, orange II, orange 

 IV, ponceau 2R, sudan R, thiazine 

 redR. 



Monocytes. When "typical" these are 

 easily recognized in stained blood smears 

 and in supravital preparations but there 

 is no technique by which they may 

 always be distinguished from all Lym- 

 phocytes and Macrophages. That is, 

 they possess no single feature, like the 

 eosinophile granules of eosinophile leuco- 

 cytes, for their certain identification 

 (see Cowdry, p. 66-71). They ingest 

 particulate matter including Trypan 

 Blue and similar vital stains and are 

 therefore to be considered as com- 

 ponents of the Reticulo-Endothelial 

 System. Alany of their properties can 

 to great advantage be investigated in 

 Tissue Cultures. The best way to 

 demonstrate the remarkably close rela- 

 tion that may exist between monocytes 

 and contained bacilli is to stain leprous 

 tissue for acid fast bacilli (see Leprosy 

 Bacilli). See Bacterium Monocyto- 

 genes. 



Monolayer technique is a physico-chemical 

 line of investigation that gives valuable 

 data on the structure of protein and 

 lipoprotein films and consequently on 

 the plasma membrane of cells. See 

 Schulmann (Bourne, pp. 51-67). 



Mordant (L. mordere, to bite), a substance, 

 like alum, employed to make a dye bite 

 into the tissue and hold on. The dye 

 combines with the mordant which is 

 itself in high concentration in the 

 structures to be stained. In the Iron 

 Hematoxylin technique the sections 

 are mordanted with iron alum. They 

 are briefly washed in aq. dest. to remove 

 some of the excess mordant. Then they 

 are stained with a dilute aqueous solu- 

 tion of hematoxylin and differentiated 

 in the mordant which draws out most of 

 the hematoxylin until it remains only 

 in the structures which took up the 

 mordant most energetically in the first 

 place and which therefore alone remain 

 colored. Copper salts are also good 

 mordants. See Weigert's mordants. 



Morosow's Method for elementary bodies as 

 modified by Fonta and Triboudeau and 

 given by Seiffert, G., Virus Diseases of 

 Man, Animal and Plant. New York: 

 Philosophical Library, Inc., 1944, 332 

 pp. Dry thin smear in air. Place 

 vertically in aq. dest., 10-15 min. and 

 dry again. Cover with mixture of 



acetic acid, 1 cc; 40% formalin (com- 

 mercial formaldehyde), 2 cc; aq. dest., 

 100 cc. Rinse well in aq. dest. and heat 

 till steam rises in mixture of carbolic 

 acid, 1 cc; tannin, 50 gm.; aq. dest., 

 100 cc Rinse in aq. dest. 3 min. and 

 heat slightly 1-2 min. till smear becomes 

 brown or slightly black in silver solu- 

 tion made up as follows: To 20 cc aq. 

 dest. add "platinum loop" of 25% am- 

 monia and then drop by drop from 

 pipette of 10% aq. silver nitrste until 

 an opalescent ppt. appears. About 

 0.5 cc. of silver solution will be needed. 

 After silvering smear rinse well in aq. 

 dest., mount and seal edges with 

 paraffin. 



Mosquito larvae, technique of raising anoph- 

 eline (Bates, M., Am. J. Trop. Med., 

 1941, 21, 103-122). Bodian technique 

 for mosquito nervous system (Rogoff, 

 W. M., Stain Techn., 1946, 21, 59-61). 



Motion Pictures. The technique of maldng 

 motion pictures of living cells and or- 

 gans has proved its worth. The movies 

 can be projected again and again and 

 the sequence of events made very clear. 

 It is important to remember that mo- 

 tile cells do not run around at the speed 

 indicated, because the actual distance 

 travelled is far less than on the screen 

 and the time much greater. The Wis- 

 tar Institute of Anatomy in Philadel- 

 phia is distributor of a comprehensive 

 series of motion picture films on either 

 a purchase or rental ba^sis. 



Motor End Plates. The particular morpho- 

 logical type of nerve ending in muscle 

 does not concern us here ; but reference 

 can be made if desired to the classifica- 

 tion by Hines, M., Am. J. Anat., 1931, 

 47, 1-55. The methods advocated for 

 histological demonstration are legion. 

 Reference is made to 2 gold techniques 

 (Craven's and Carey's) and to 1 silver 

 method (Chor's). The former can be 

 ultimately traced back to Ranvier and 

 the latter to Cajal. See also techniques 

 described under Nerve Endings. 



Mounting Media. The refractive index of 

 the medium is important and a table 

 giving the indices for many substances 

 used is supplied by Lee (p. 218). As 

 pointed out, the greatest transparency is 

 secured when the refractive indices of 

 media and tissues are equal and media of 

 lower index than the tissues give some- 

 what greater visibility of tissue com- 

 ponents, while those of higher index 

 provide less visibility. There are many 

 media to choose from, the refractive 

 indices of which are more or less satis- 

 factory. The selection will depend 

 more upon whether the medium can be 

 employed for the particular tissue and 

 its relative permanence. 



