DUGGINS 



104 



DUST CELLS 



must be determined by trials, remove a 

 piece of it, tease out a small lobule and 

 examine under low power mounted in 

 0.85% aq. sodium chloride. The com- 

 plicated system of ducts should be 

 sharply delineated by their deep rose 

 red color in an almost colorless 

 background. If there is any question of 

 their identification examine the original 

 figures of Bensley, R. R., Am. J. Anat., 

 1911, 12, 297-388. A double staining of 

 ducts and Islets of Langerhans can be 

 obtained by perfusing in the same way 

 with pyronin solution to 1000 cc. of 

 which 6 cc. 1% aq. neutral red has been 

 added. The islets appear yellow red in 

 contrast to the rose red ductules. See, 

 in addition, ducts in whole mounts of 

 Mammary Glands and in sections of 

 Submaxillary Glands which are of par- 

 ticular interest in detecting the action of 

 salivary gland viruses. 



Duggins, see Hairs 



Duodenal Fluid. Microscopic study must 

 be prompt because of the presence of 

 cytolytic engymes. Examine sediment 

 after centrifugal concentration as in the 

 case of urinary sediments. Epithelial 

 cells from the entire alimentary tract 

 leading to and including the duodenum 

 may be present, generally bile stained, 

 also a few neutrophiles. A great in- 

 crease in both or either may indicate 

 inflammatory lesions. A polarizing mi- 

 croscope is helpful, but not essential, 

 in recognizing cholesterol crystals as 

 thin, flat, colorless fragments with 

 chipped edges. The more irregular the 

 crystals the more significant they are 

 of calculi formation. Bilirubin is easily 

 detected as amorphous amber, brown or 

 black material and calcium bilirubinate 

 as bright yellow granular deposits. 

 See Gentzkow and Van Auken in Sim- 

 mons and Gentzkow, p. 63. 



Duodenal Drainage Smears, see Papani- 

 colaou Techniques. 



Duran-Reynals, see Spreading Factors. 



Dust Cells of the Lungs— Written by C. C. 

 Macklin, Dept. of Histological Re- 

 search, The University of Western On- 

 tario, London, Canada. November 28, 

 1951 — These phagocytes develop in the 

 alveolar walls of the lungs of man and 

 other mammals from the primitive 

 pneumonocy tes to arrest particles of car- 

 bon and other particulate matter which 

 elude the apprehensional mechanism of 

 the respiratory tract; and to dispose of 

 them by conveying them to the ciliary 

 escalator which evacuates them. Col- 

 lapse of the lungs dislodges them from 

 their normal position in the alveolar 

 wall (Macklin, C. C, Lancet, Feb. 24, 

 1951, 432-435) where they are wedged 

 in between capillaries, whence they 



derive their nutriment. Thus the ordi- 

 nary human lung material available 

 to pathologists is unfavorable in that 

 it shows phagocytes lying loose which 

 normally are tethered. If the skin and 

 outer musculature be removed from a 

 fresh intact thorax of a small animal 

 such as the mouse and it be at once im- 

 mersed in a fixing fluid such as Regaud 

 or Bouin's, the lung is quickly fixed in 

 its normal uncollapsed condition. Pen- 

 etration is facilitated by exposing the 

 lower surface of the diaphragm, but this 

 must not be breached. Sections from 

 such material show as many as 99% or 

 more of the dust cells morphologically 

 affixed to the alveolar walls, while only 

 1% or less are free, and these are re- 

 garded as spent and on their way to 

 the exterior. If, however, fresh normal 

 mouse lungs are collapsed and promptly 

 filled with fixing fluid via the trachea, 

 and cut into sections, it is found that 

 only about 5% of the dust cells remains 

 fixed in the alveolar walls, the re- 

 mainder now appearing free. An er- 

 roneous picture of the relation of the 

 dust cells to the alveolar walls is thus 

 presented. That collapse alone dis- 

 lodges many of the phagocytes formerly 

 affixed in the alveolar walls is shown by 

 finding undue numbers of free dust cells 

 in sections from pieces of lung tissue 

 which have been fixed by immersion. 

 For larger lungs the method of perfusion 

 of fixing solution through the pulmo- 

 narvvasculature of the unopened thorax 

 (Hartroft, W. S., Anat. Rec, 1942, 82, 

 419) also showed the majority of alveo- 

 lar phagocytes affixed to the walls rather 

 than free. Thus dust cells are funda- 

 mentally mural phagocytes, and are 

 regarded as originated ultimately from 

 endodermal epithelium (Macklin, C. C, 

 Trans. Roy Soc. of Canada, Sect. V, 

 1946, 40, 93-111) . The presence of fluid 

 in the alveoli favors a shedding of mural 

 phagocytes from their walls. No ev- 

 dence of dust cell entry into the con- 

 nective tissue or lymphatic channels 

 of the lung was found, contrary to the 

 opinion of many pathologists. On the 

 other hand, dust cells are often found 

 stuck in the mucus overlying the epi- 

 thelium of the bronchioli and bronchi, 

 and these are probably wornout cells 

 being carried to the glottis by ciliary 

 movement (Macklin, C. C, Can. J. 

 of Res., D, 1949, 27, 50-58; Macklin, 

 C. C, Proc. Instit. of Med. of Chicago, 

 1950, 18, 78-95). They are recoverable 

 from sputum, and then have been re- 

 ferred to by the unsuitable term "heart 

 failure cells" (which see). 



In the mouse most alveolar phago- 

 cytes are in alveolar angles and have 



