EIMERIA 



111 



ELASTICA-TRICHROME STAIN 



Eimeria, see Coccidia. 



Einarson, see Gallocyanin-Chromalum 

 Staining of Basophilic Cell Structures. 



Elacin, see Elastic Fibers. 



Elastase. An elastolytic enzyme from pan- 

 creas has been reported by Bal6, J. and 

 I. Banga, Biochem. J., 1950, 46, 384- 

 387. This enzyme renders elastic tis- 

 sue soluble, without the formation of 

 amino acid residues. Consequently, it 

 apparently depolymerizes elastin. 

 Since elastic tissue is highly insoluble, 

 this enzyme should prove most useful 

 both for chemical and histological in- 

 vestigations. 



Elastic Fibers — Written by A. I. Lansing, 

 Dept. of Anatomy, Washington Uni- 

 versity, St. Louis 10, Mo. October 5, 

 1951 — Viewed in fresh unstained spreads 

 of Loose Connective Tissue these fibers 

 are generally yellow and are more highly 

 refractile than coUagenic fibers. They 

 are optically homogeneous, branch re- 

 peatedly to form networks, are of vari- 

 able thickness and do not swell in dilute 

 acids. Elastic fibers are resistant to 

 both pepsin and pure trypsin and are 

 slowly digested in commercial grade 

 trypsin. The latter may be due to 

 contamination by elastase, a new, rela- 

 tively specific enzyme which solubilizes 

 elastic fibers (Bal6, J. and Banga, I., 

 Biochem J., 1950, 46, 384). Elastic 

 fibers are also solubilized by prolonged 

 boiling in 0.25 N oxalic acid (Adair, G. 

 S., Nature, 1951, 167, 605). 



Elastin may also be distinguished 

 from collagen by its amino acid compo- 

 sition. As indicated in the accompany- 

 ing table, collagen is very rich in hy- 

 droxyproline while elastin has only 

 small amounts. Not all elastins have 

 the same amino acid compositions. 

 Ligamentum nuchae (cow) differs sig- 

 nificantly from elastin of human arteries 

 which differ from one another. Indeed 

 age influences the amino acid composi- 

 tion of elastin from human aortas. 



Age influences many of the properties 

 of elastic tissue. Senile elastic tissue 

 of skin is often called elacin. This 

 material is not unlike elastic tissue in 

 old arteries. Age differences in elastic 

 tissue may be summarized as follows: 

 Elastic fibers are readily demon- 

 strated in sections by the use of one of 

 several fairly specific stains including 

 Weigert's Resorcin-Fuchsin, Verhoeff's 

 Hematoxylin Stain, Unna's Orcein 

 Method, Krajian's Congo Stain. After 

 oxidation elastic fibers are colored red 

 by the Schiff Reagent. Victoria blue 

 and Basic Fuchsin also effectively stain 

 elastic fibers. 

 When viewed with polarized light 



elastic fibers are not birefringent but 

 become so when stretched. This would 

 suggest that, although the fibers are 

 optically homogeneous, they possess 

 internal structural orientation. Elec- 



Amino Acid Composition of Collagen and Elaslin* 



Amino Acid 



Total N 



Glycine 



Alanine 



Leucine 



Isoleucine 



Valine 



Phenylalanine. .. 



Tyrosine 



Tryptophan 



Serine 



Threonine 



Cystine 



Methionine 



Proline 



Hydroxyproline . 



Lysine 



Hydroxylysine. . 



Arginine 



Histidine 



Aspartic acid .... 

 Glutamic acid. . . 

 Amide N 



< 



& 



rt 

 a 

 o 



a 



3 



C.S 



gN per 100 gN 



18.6 

 26.2 

 9.5 

 3.22 

 2. IS 

 3.4 

 4.2 

 1.4 

 0.0 

 3.4 

 2.4 

 0.0 

 0.8 

 15.1 

 14.0 

 4.5 

 1.3 

 8.8 

 0.8 

 6.3 

 11.3 

 0.66 



Total found 119.00 



15.56 



21.30 



21.58 



4.76 



2.33 



11.50 



1.97 



1.76 



0.24 



0.70 



1.13 



0.10 



0.35| 



9.20i 



1.17 



4.35 

 0.75 

 l.Il 

 3.01 

 2.86 



16.00 

 32.00 



4.78 

 2.28 

 12.9 



90.17 



11.0 



0.62 

 1.75 

 1.51 



• Adapted in part from Gross: J. Gerontol., 1950, 5, 

 343. 



t Bowes, J. H., and Kenton, R. H.: The amino acid 

 composition and titration curve of collagen. Biochem. 

 J., 1948, 43, 358-365. 



t Neuman, R. E.: Amino acid composition of gela- 

 tins, coUagens and elastins from different sources. Arch. 

 Biochem., 1949, 24, 289-298. 



§ Lan.sing, A. I., Roberts, Eugene, Ramasarma, G. 

 B., Rosenthal, Theodore B., and Alex, Morris: Changes 

 with age in amino acid composition of arterial elastin. 

 Soc. Exp. Biol. Med., 1951, 76, 714-717. 



tron microscopy has so far failed to 

 reveal internal structure. Elastic fibers 

 partially digested with elastase do re- 

 veal the presence of intertwined fibrils. 



Elastic Properties, see Surface Tension. 



Elastica-Trichrome Stain. In order to 

 demonstrate elastic fibers with equal 

 clearness to the smooth muscular and 

 collagenic fibers, especially in the walls 



