MUCUS 



160 



MUSCLE 



of mucus is not uniform . It may consist 

 of one of several glycoproteins, called 

 mucins, which are by contrast definite 

 chemical substances. The term mu- 

 cous is an adjective describing a cell or 

 tissue which produces or contains 

 mucus. Mucigen is the intracellular 

 antecedent of a mucin. Since there are 

 several mucins there are several corre- 

 sponding mucigens. 



Pathologists sometimes divide mucins 

 into two categories, epithelial and con- 

 nective. The connective tissue type is 

 found in the ground substance of bone, 

 synovial fluid and in other locations. 

 It increases in amount in the myxedema 

 (G. myxa, mucus + oidema, swelling) 

 of certain thyroid deficiencies as well 

 as in arteriosclerosis and various tumors. 

 The ubiquitous fibroblast is said to be a 

 great former of mucins. Epithelial 

 mucins are produced by epithelial 

 secretory cells. The goblet cells are 

 easily recognized by the fact that the 

 material to be discharged is held in a 

 goblet like expansion of the cell. Other 

 mucous cells can be distinguished from 

 serous or zymogenic cells by several 

 criteria: 



1. The nuclei instead of being roughly 

 spherical are often, but not always, 

 pressed against the cell membrane re- 

 mote from the lumen. 



2. The mitochondria are usually of 

 smaller diameter and shorter than in 

 zymogenic cells. 



3. The secretion antecedents (Muci- 

 gens) of mucous cells are more difficult 

 to see in the fresh state, more labile, 

 and in fixed tissues are metachromatic 

 and can be stained almost specifically 

 with mucicarmine and mucihematein. 



See Mucicarmine and Mucihematein 

 of Mayer. 



A simple method for mucus has been 

 described by Lillie (R. D., J. Tech. 

 Methods, 1929, 12, 120-121). Sections 

 of tissue fixed in formalin or in Zenker- 

 formol (Helly) are passed to water. In 

 the case of the latter remove mercury 

 with iodine and sodium thiosulphate as 

 usual. Stain 1 min. in 0.2% aq. toluidin 

 blue. Wash in water. Dehydrate in 

 pure acetone, clear in xylol and mount in 

 balsam. Mucus, reddish violet; nuclei, 

 blue ; red cells, yellow or greenish yellow. 

 In the case of old formalin material 

 rinse in 95% alcohol before the acetone. 



McManus, J. F. A., Nature, 1946, 158, 

 202, recommends the use of Schiflf's 

 Reagent followed by periodic acid. 

 Material fixed in Zenker-formal is de- 

 hydrated and embedded in the usual 

 manner and the sections transferred to 

 water after treatment with iodine and 

 hypo and placed in a 0.5% aq. periodic 



acid 2 min. The slides are washed in 

 tap water and aq. dest. and kept in 

 Schiff's reagent for 15 minutes; rinsed 

 in Sulphurous Acid, dehydrated and 

 cleared in the alcohol and xjdol series 

 respectively and mounted in balsam. 

 According to McManus, the mucus of 

 the goblet cells of the human intestine 

 and bronchus, mucus salivary glands, 

 certain pituitary cells, the colloid of the 

 pituitary stalk and thyroid, granules 

 in some nerve cells in the medulla of the 

 rat and in the human intestine, the 

 basement membranes of the tubular 

 epithelium and of the glomerulus in the 

 kidney were tested by this method and 

 an intense coloration detected in all 

 instances. 



Miiller's Fluid. Potassium bichromate, 2- 

 2.5 gm.; sodium sulphate, 1 gm.; aq. 

 dest., 1 gm. This was formerly much 

 used for long fixation and mordanting of 

 nervous tissue. See Chromaffin Reac- 

 tion, Decalcification, O'Leary's Bra- 

 zilian Method, Weigert Method. It is 

 now largely replaced by Orth's Fluid 

 which is really formalin-Miiller. 



Mumps. Refractile, eosinophilic bodies in 

 red blood cells are very small first 5-6 

 days. Increase in size and elongate 

 7-14 days. (Parsons, H. H., Military 

 Surgeon, 1938, 83, 541-543). 



Muscle, to distinguish in sections from con- 

 nective tissue, Dahlgren (McClung, p. 

 306) suggests Retterer's and Van 

 Gieson's stains, picronigrosine and 

 Unna's orcein to which may be added 

 Mallory's stain. Demonstration of 

 chloride in muscle fibers (Heilbrunn, 

 L. V. and Hamilton, P. G., Physiol. 

 Zool., 1942, 15, 363-374). For contrac- 

 tion bands and vrave mechanics, see 

 Carev, E. J., Arch. Path., 1940, 30, 

 881-892, 1041-1072. A technique for 

 separating nuclei from cytoplasm for 

 analysis is given under Nuclei. If 

 microdissection is contemplated the 

 pioneer paper by Kite, G. L., Am. J. 

 Physiol., 1913, 32, 146-164 should be 

 consulted. The experimental produc- 

 tion of myocardial segmentation is 

 described by Saphir, O. and Karsner, 

 H. T., J. Med. Res., 1923-24, 44, 539- 

 556. Methods of Maceration are often 

 useful in the isolation of single fibers. 

 Mitoses can only be induced in excep- 

 tional cases (Allen, E., Smith, G. M. 

 and Gardner, W. U., Am. J. Anat., 

 1937, 61, 321). An electron microscopic 

 technique for localization of magnesium 

 and calcium is described by Scott, G. 

 H. and Packer, D. M., Anat. Rec, 

 1939, 74, 31-45. Muscle gives beautiful 

 fluorescent colors in ultraviolet light 

 with many fluorochromes (Metcalf, 

 R. L. and Patton, R. L., Stain Techn., 



