ALTMANN'S METHOD 



22 



ALVEOLAR EPITHELIUM 



magnificent original plates should be 

 examined (Altmann, R., Die Elementar- 

 organismen und ihre Beziehungen zu den 

 Zellen. Leipzig: Veit Co., 1894, 160 

 pp.). If these are not available see 

 Meves, F., Arch. f. mikr. Anat., 1913, 

 82, (2), 215-260. 

 Altmann-Gersh frozen-dehydration method 

 (Gersh, I., Anat. Rec, 1932, 53, 309- 

 337). — Account written by Dr. Gordon 

 H. Scott, Dept. of Anatomy, Wayne 

 University School of Medicine, De- 

 troit, Mich. This method has proved 

 to be of much value in the preparation 

 of tissues for microchemical proce- 

 dures. It has also been used as a pre- 

 liminarj' treatment for tissues destined 

 for examination by the electron micro- 

 scope (Wyckoff, "R. W. G., Science, 

 1946, 104, 21-26). Tissues are frozen 

 in liquid nitrogen or in liquid oxygen 

 and dehydrated in vacuo at low tem- 

 peratures. The tissue sample remains 

 frozen at such a temperature that little 

 or no chemical change can take place. 

 It is believed that the only significant 

 revision in cellular organization takes 

 place during the freezing process. This 

 is occasioned by possible shifts in pro- 

 teins, etc., during ice crystal formation. 

 Some users of the method believe that it 

 is possible to freeze small tissue samples 

 at speeds which will actually prevent 

 ice crystal formations. Efforts in this 

 direction have been made by freezing 

 in cooled iso-pentane (technical) 

 (Hoerr, N. L., Anat. Rec, 1936, 65, 293- 

 317; Simpson, W. L., Ibid., 1941, 80, 

 173-189). 



For many reasons it has been found 

 desirable to dehydrate at lower tem- 

 peratures than were first thought neces- 

 sary. Now the standard procedure is 

 to dehydrate in vacuo from 40-65°C. 

 Apparatus of special design has been 

 constructed a number of times to meet 

 various needs. In general the prin- 

 ciples are the same. What is needed 

 is a vacuum system with high pumping 

 speed and with provision for keeping 

 the frozen tissue at constant tempera- 

 ture. Several of these have been de- 

 scribed, each with its adaptation to the 

 needs of the case. 



For general use in histochemistry the 

 device described by Packer and Scott 

 (J. Tech. Methods, 1942, 22, 85-96) and 

 by Hoerr and Scott (Medical Physics, 

 Otto Glasser, 1944, Year Book Pub- 

 lishers) is both easy to operate and re- 

 liable. It has the distinct advantage 

 that tissues can be infiltrated with 

 paraffin without exposure to air. This 

 apparatus can also be used for the 

 preparation of tissues for electron 

 microscopy. For this use only the de- 



hydration device described by Wyckoff 

 is probably more suitable. 



Alum. The alums are double salts of sul- 

 phuric acid. Aluminum potassium sul- 

 phate, or potassium alum, unless other- 

 wise stated is the one used in making up 

 hematoxylin solutions. Aluminum am- 

 monium sulphate, or ammonia alum, 

 should not be used as a substitute unless 

 called for. Ammono-ferric sulphate, or 

 iron alum is used as a mordant and differ- 

 entiator in the iron hematoxylin tech- 

 nique and for other purposes. The 

 crystals are of a pale violet color. Their 

 surfaces oxidize readily and become use- 

 less. The surface should be scraped off. 

 Only the violet crystals are of any use. 



Alum-Carmine (Grenacher). Boil 1-5% aq. 

 ammonia alum with 0.5-1% powdered 

 carmine. Cool and filter. Does not 

 penetrate very well and hence is not 

 suitable for staining large objects in 

 bulk. But it is useful and does not 

 overstain (Lee, p. 140). 



Alum Hematoxylin. Many hematoxylin so- 

 lutions contain alum, see Delafield's, 

 Ehrlich's, Harris', Mayer's. 



Aluminium Chloride Carmine (Mayer). 

 Dissolve 1 gm. carminic acid and 3 gm. 

 aluminium chloride in 200 cc. aq. dest. 

 Add an antiseptic as formalin or 0.1% 

 salicylic acid. Employ in same way as 

 carrnalum. Gives blue violet color. 

 Very penetrating but not so specific for 

 chromatin as carmalum (Lee, p. 142). 



Alveolar Epithelium of Lungs 



1. Gold sodium thiosulphate (Bensley, 

 R. D. and S. H., Anat. Ilec, 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 bj" 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. D. and S. 



