ARTERIOVENOUS ANASTOMOSES 29 



ASTRA VIOLET 



about 35m (Grant, R. T. and Bland, 

 E. F., Heart, 1930, 15, 385-411). The 

 best way is to study them in vivo (Clark, 

 E. R. and E. L., Am. J. Anat., 1934, 55, 

 407-467). 



Arteriosclerosis. The arteries in this condi- 

 tion show changes well demonstrated 

 by Mallory's Connective Stain and its 

 modifications as well as by Weigert's 

 Resorcin Fuchsin. In addition, tech- 

 niques for Lipids, Calcium and Iron are 

 indicated. Methods for the measure- 

 ment of physical properties of arteries 

 might well be applied to arteries most 

 and least prone to develop arterio- 

 sclerosis. These are summarized by 

 Bramwell, C, in Cowdry's Arterio- 

 sclerosis. New York: Macmillan Co., 

 1933, 617 pp. 



Articular Nerve Terminals. Gardner, 

 E. D., Anat. Rec, 1942, 83, 401-419, 

 working in our laboratory, adapted 

 silver methods to the demonstration of 

 nerve terminals associated with the 

 knee joints of mice 1-60 days old. 

 Subsequently, J. Comp. Neur., 1944, 

 80, 11-32, similar methods were applied 

 to the knee joints of 33- and 46-day-old 

 cat fetuses. 10% and 20% formalin 

 and Bouin's fluid were the fixatives em- 

 ployed. Wash, dehydrate to 70% al- 

 cohol. Decalcify in 2.5% nitric acid in 

 70%o alcohol. Wash in 70% alcohol 

 until neutral to blue litmus paper. 

 Dehydrate and infiltrate with nitro- 

 cellulose dissolved in methyl benzoate. 

 Harden in chloroform, clear in xylol 

 and leave in half paraffin and xylol over 

 night at 37°C. Imbed in paraffin and 

 cut lO/n sections. Subsequently the 

 Bodian technique is followed, leaving 

 the sections in protargol (Winthrop) 

 12-48 hrs. Axones stain black against 

 a reddish gray background whose den- 

 sity may be varied according to the 

 length of treatment with oxalic acid. 

 To obtain consistent results chemically 

 clean glassware and doubly distilled 

 water are helpful. Most difficulties, 

 however, are due to improper fixation. 

 Fixatives with heavy metals should be 

 avoided. Formalin should be neutral- 

 ized, preferably with MgCOs- Bouin's 

 fluid is especially good for fetal mate- 

 rial and is equal to formalin for young 

 and adult material. (Revised by E. D. 

 Gardner, Dept. of Anatomy, Wayne 

 University School of Medicine, De- 

 troit, Mich., 1946.) 



Artifacts. Webster defines an artifact as 

 being "in histology, a structure or 

 appearance in a tissue or cell due to 

 death or to the use of reagents and not 

 present during life." The degree of 

 artifact is proportional to the difference 

 between the structure existing normally 



in the living body and the structure in 

 the condition directly studied. 



1. In the case of living tissues, ob- 

 served with blood and nerve supply 

 intact, there is a possibility of artifact. 

 It is at a minimum in the Rabbit Ear 

 Chambers and rather more to be reck- 

 oned with when tissues must be dis- 

 placed in order to supply the necessary 

 illumination. With increase in time 

 modifications due to changes in light, 

 temperature, hydrogen ion concentra- 

 tion, etc. are likely to also increase. 



2. In living cells removed from the 

 body and examined in Tissue Cultures 

 the possibility of artifact is again at a 

 minimum; but, though the cells in suc- 

 cessive generations in suitable media go 

 on living indefinitely, their environ- 

 ments are different from those e.xisting 

 within the body. When after Vital 

 Staining or Supravital Staining still 

 living cells are examined in approxi- 

 mately isotonic media, there is a grave 

 danger of artifact if the study is pro- 

 longed because the cells are slowly dying. 



3. In fixed tissues the degree of di- 

 vergence from the normal living condi- 

 tion is obviously much greater than in 

 the case of still living ones. However 

 death has been sudden so that artifacts 

 due to gradual death are eliminated. If 

 the technique has been carefully stand- 

 ardized the same fixative applied to the 

 same type of cell in the same physiologi- 

 cal state is likely to yield similar results. 

 Among common artifacts are: 1. The 

 shrinkage and increased affinity of cells 

 near the surface for stains due to allow- 

 ing the surface of the tissue to dry be- 

 fore fixation. 2. The glassy appearance 

 of nuclei and cytoplasm sometimes oc- 

 casioned by overheating in imbedding 

 or in spreading out sections. 3. Mate- 

 rial within blood vessels faintly resem- 

 bling organisms caused by coagulation 

 of blood proteins. 4. Extraneous sub- 

 stances either present in the albumen 

 fixative used to mount the sections or 

 deposited as dust from the air. Careful 

 focussing is required. See Agonal and 

 Postmortem changes. Ice Crystal Arti- 

 facts. 



Artificial Fever, influence on adrenal (Bern- 

 stein, J. G., Am. J. Anat., 1940, 66, 

 177-196). See Cramer, W., Fever, 

 Heat Regulation and the Thyroid- 

 Adrenal Apparatus. London: Long- 

 mans, Green & Co., 1028, 153 pp. 



Ascorbic Acid, see Vitamin C. 



Aspirated Sternal Marrow, method for 

 preparing smears and sections (Gordon, 

 H., J. Lab. & Clin. Med., 1940-41, 26, 

 1784-1788). 



Astra Violet, see Leishmania. 



