NORMALITY, MICROSCOPIC 



235 



NORiMA] JTY, MICROSCOPIC 



tissues care is indicated that the 

 samples are truly representative of the 

 whole. Examination of samples all 

 from the tail of the pancreas well might 

 fail to reveal conditions prevalent else- 

 where in the pancreas and convey a false 

 idea of the normality of the whole. 

 Inadequate preliminary gross examina- 

 tion might lead to the overlooking of 

 small localized modifications, as in 

 beginning cancers, and might result 

 in a verdict of normality based on ap- 

 pearances in poorly selected samples. 



3. If the samples have been taken 

 from organs or tissues which are larger 

 (hypertrophied) or smaller (atrophied) 

 than normal then their examination 

 may likewise result in a misconception 

 of normality. The alterations in 

 volume, which have to be taken into 

 consideration, may be abnormal, or 

 within the range of normal volumetric 

 changes in physiological activity. 

 Among the latter are alterations in 

 the volume of the liver consequent upon 

 the different phases in intestinal ab- 

 sorption. We must face not only 

 changes in volume but also changes 

 in microscopic appearance. The nor- 

 mality of microscopic structure there- 

 fore must be specified in relation to 

 physiologic state. What is normal for 

 one stage in the menstrual cycle is not 

 normal for another.What is normal for 

 the gastric mucous membrane during 

 active digestion is not normal while 

 fasting. 



4. Since the appearance depends upon 

 the technique employed the qualifica- 

 tion is essential that it is normal for, 

 say, intracellular lipids demonstrable 

 by Sudan III, or for whatever is in 

 question. Not all lipids are detectable 

 by this method. It is quite possible 

 that the lipid contents not so revealed 

 are in abnormal quantities. 



5. In returning a verdict that tissues 

 examined microscopically are normal, 

 histologists should still further qualify 

 their conclusions. It is the part of 

 wisdom for them to remember, es- 

 pecially when employing microchemical 

 reactions, that most of them are ig- 

 noramuses as to chemistry. A smatter- 

 ing of chemistry is insufficient. It is 

 a kind of wine that goes to the head 

 releasing inhibitions. Not to obtain 

 expert advice from real chemists is 

 foolish. 



Consider only the sections of tissues 

 fixed in formalin, or in Zenker's fluid, 

 and stained with hematoxylin and eosin 

 which are examined routinely in so 

 many laboratories. Reflect upon the 

 functional attributes of these tissues 

 while they were alive and to changes 



to which these specimens give no clues 

 whatsoever. Among these are respon- 

 siveness to stimuli, permeability, the 

 entry and outgo of water and of in- 

 numerable substances, the integration 

 of thousands of enzymatic activities, 

 the basic submicroscopic structural ar- 

 chitecture that makes this possible, 

 and so on almost ad infinitum. It is 

 no wonder that tissues examined by 

 such a crude technique, as well as by 

 other more delicate ones, may look 

 normal, since so much is overlooked, 

 while in fact they are far from normal. 

 Neuroanatomists are among the first 

 to recognize the inadequency of micro- 

 scopic examinations. They designate 

 abnormalities without structural traces, 

 "functional." Parts of the brain that 

 look normal actually may be far from 

 normal. This qualification probably 

 holds for all parts of the body. 



Standards for the comparison are 

 few and disappointing. Some gross 

 weights and measurements are given 

 in Laboratory Technique but these are 

 only for adults and corrections for race 

 are not supplied. For a summary of 

 measurements for children see R. E. 

 Scammon's account in Abt's Pediatrics, 

 Philadelphia: Saunders, 1923, 1, 257- 

 444. Anatomische, Physiologische und 

 Physikalische Daten by H. Vierordt, 

 Jena: Fischer, 1906, 616 pp. is still use- 

 ful. R. Pearl and his associates have 

 published quantitative data on the 

 endocrines in Human Biology, 1935, 7, 

 350-391; 555-607. 1936, 8, 92-125. 

 1937, 9, 245-250. For a spleen and 

 thymus see E. B. Krumbhaar in 

 Cowdry's Problems of Ageing, 1942. 

 The Tabulae Biologicae (Amsterdam: 

 Vitgevery, Dr. W. Jurik) is often use- 

 ful. The last part on the eye (oculus) 

 constitutes vol. 22 of 408 pp. and was 

 published in 1947. The most recent 

 publication on normal values in clinical 

 medicine is that of Sunderman and 

 Boerner (1949). A "Handbook of Bi- 

 ological Data" is in course of organiza- 

 tion by the American Institute of Bi- 

 ological Sciences under the direction 

 of E. C. Albritton at the National Re- 

 search Council, Washington, D. C. 



Summary: Histologists must be alert 

 for artifacts, for otherwise there is a 

 danger of describing appearances not 

 present in vivo, or exaggerated or min- 

 imized by the procedure employed. 

 They must be good physiologists always 

 mindful of the fact that only a minority 

 of functional states are reflected by 

 microscopic structure. They must re- 

 member that their techniques just skim 

 the surface. As experimentalists it is 

 essential for them to gain a knowledge 



