ALVEOLAR EPITHELIUM OF LUNGS 8 



ALVEOLAR PORES 



Alyeolar Epithelium of Lungs 



1. Gold sodium thiosulphate (Bensley, 

 R. D. and S. H., Anat. Rec, 1935, 64, 

 41-49). Inject a mouse intravenously 

 through the tail vein with 100 mg. of 

 gold sodium thiosulphate in 1 cc. aq. 

 dest. The mouse dies in about 20 min. 

 from asphyxia. Fix pieces of lung in 

 10% neutral formalin, dehydrate with- 

 out washing in water, clear and imbed 

 in paraffin. Deparaffinise sections and 

 stain in 1% aq. toluidin blue (tested 

 for polychromatism) and examine in 

 water. The epithelium is raised by in- 

 crease in volume of ground substance 

 which is stained metachromatically 

 pink while the cells and their nuclei are 

 blue. The color of the ground sub- 

 stance can be changed to blue by alco- 

 hol and back again to pink by water. 

 To mount protect against reversing 

 action of alcohol by treating with equal 

 parts freshly prepared 5% aq. am- 

 monium molybdate (Kahlbaum or 

 Merck) and 1% aq. potassium ferro- 

 cyanide. Dehydrate, clear in xylol 

 and mount in balsam. (Revised by 

 R. D. and S. H. Bensley, Dept. of 

 Anatomy, University of Chicago, Chi- 

 cago, 111., April 18," 1946.) 



2. Silver nitrate (Bensley, R. L). and S. 

 H., Anat. Rec, 1935, 64, 41-49). Use 

 guinea pigs. Silver Citrate sol. (which 

 see) is injected into lung substance by 

 hypodermic syringe, the roots of the 

 lung being first ligated, until the lung 

 is moderately distended. Cut out 

 pieces, fix in 10% formalin, imbed in 

 paraffin or celloidin, section, develop 

 with dilute photographic developer and 

 counterstain or examine unstained. 

 The margins of the cells are blackened. 

 For the most delicate results a slow 

 acting, fine grain developer such as the 

 following should be used: phenyl hy- 

 drazine hydrochloride, 1 gm., sodium 

 sulphite (anhydrous), 10 gm.; aq. dest., 

 100 cc. Caution: Phenyl hydrazine 

 hydrochloride is extremely toxic to 

 some people producing skin reactions. 

 (Revised by R. D. and S. H. Bensley, 

 April 18, 1946.) 



Alveolar Fluid. Method for collecting, 

 Terry, R. J., Anat. Rec, 1926, 32, 223- 

 304; 1936, 64, 75. 



Alveolar Foam Cells. — Written by C. C. 

 Macklin, Dept. of Histological Re- 

 search, The University of Western 

 Ontario, London, Canada. November 

 28, 1951. — These represent nonphago- 

 cytic pneumonocytes which have be- 

 come free in the alveoli and air tract 

 of the lungs. They may be obtained 

 by the "gash-irrigation" and "wash- 

 out" techniques (which see). Macklin 

 found in them refractile vacuolelike 



bodies or vacuoloids (which see) readily 

 demonstrable in fresh mounts by bright- 

 or dark-field illumination (Proc 6th 

 International Congress of Experimental 

 Cytology, Stockholm, 1947, published 

 1949, pp. 383-387). In ordinary sec- 

 tions these bodies appear empty or with 

 a very small granule within them. 

 When foreign particles appear in them 

 they are known as "Dust Cells" (which 

 see). Mitochondria in foam cells are 

 mainly in the frothy perivacuoloidal 

 cytoplasm (Macklin, C. C, Biol. Bull., 

 1949,96, 173-178). 



Alveolar Phagocytes of Lungs, see Dust 

 Cells. 



Alveolar Pores of the lung.^Revised by 

 C. C. Macklin, Dept. of Histological 

 Research, The University of Western 

 Ontario, London, Canada. November 

 28, 1951— Formalin (10%) and Zenker- 

 formalin are among the fixatives sug- 

 gested. The fixative is injected into 

 the trachea or bronchus at a gravity 

 pressure of 4-6 inches until the lungs 

 are moderately distended. During this 

 operation they are covered with physio- 

 logical salt solution. The lungs are 

 then immersed in fixative for days or 

 even weeks. Slices about 1 cm. thick 

 are cut, imbedded in soft paraffin and 

 sections are made at 100/i or more. 

 Resorcin-fuchsin and other stains may 

 be used. The blood in the capillaries 

 is a useful guide. The pores can be 

 identified by their rounded edges 

 (Macklin, C. C, Arch. Path., 1936, 21, 

 202-216). 



In lungs fixed by immersion of the 

 flayed intact thorax (IIT) or perfusion 

 of the pulmonary capillaries of the in- 

 tact thorax (PIT) the pores, in thick 

 sections, appear as short narrow tunnels 

 with funnel-shaped entrances joining 

 neighboring alveolar spaces. Their ex- 

 tremely thin walls are composed of parts 

 of the contiguous capillaries. (See 

 "Fixation of the Uncollapsed Lung" 

 and "Dust Cells".) Thus seen a pore 

 is the empty sheath or vagina from 

 which a process of a pneumonocyte 

 (septal cell, alveolar wall cell, etc.) has 

 been withdrawn. When such a process 

 cannot be withdrawn because it is bul- 

 bous the cell is seen as a dumbbell - 

 shaped structure with the thin con- 

 necting part in the pore. In its func- 

 tional state this vagina is occupied by 

 a part of a pneumonocyte, and the latter 

 is thus placed where nutrition from the 

 capillaries is constantly available. 

 Any good fixative suffices to show pores 

 by these methods. When pieces of 

 lung tissue are fixed by immersion the 

 ensuing contraction usually closes the 

 pores to that they cannot be seen 



