62 



(a) Picro-fuchsin. See 119. This may be used with or with- 

 out a basic counter-stain which should precede it. If a counter- 

 stain is used remember to overstain and use the picro-fuchsin to dif- 

 ferentiate it. 



(b) Orange-fuchsin. Formula: Fuchsin acid, 2 grams; Orange 

 G., 1 gram; Glycerin, 7 c. c.; distilled water, 100 c. c. Fix tissue in 

 Flemming's fluid. Stain sections 30 seconds; dehydrate, clear, and 

 mount in balsam (not alkaline) . Suitable also for staining the reticu- 

 lar tissue (lymphatic tissue). 



Somewhat more delicate than the picro-fuchsin. 



(c) Mallory's connective tissue stain. See 120. While not a 

 differential stain for collaginous fibers, it is nevertheless a valuable one, 

 and frequently to be preferred. 



181. Elastic Fibers (Elastin). Employ either the Weigert 

 ResorchvFuchsin or the Orcein methods ( 125, 126), or the Verhoeff 

 [44] method ( 127). 



Both the white and elastic fibers may be stained in the same 

 preparation, the elastic fibers being stained first. 



In a mixture composed of white and elastic fibers, picro-fuchsin 

 ( 119) will stain the elastic fibers a light yellow, the white fibers being 

 colored red. 



In studying the connective tissues, it should be remembered 

 that acetic and the mineral acids cause swelling or solution (gelatini- 

 zation) of the white fibers, depending upon their strength. While 

 this improves the cutting quality of organs rich in connective tissue, 

 it also causes vagueness in outline of the white connective tissue 

 fibrils. It may therefore be advisable to decrease the percentage of 

 acetic acid in the fixer when the connective tissue is under investi- 

 gation. 



182. Reticular Tissue. Fuchsin acid, Mallory's connective 

 tissue stain, or the orange-fuchsin acid mixture may be chosen for 

 staining this form of connective tissue. As however the cellular ele- 

 ments usually mask the fiber relations, if a view of the latter is desired 

 the cells must be removed, by a mechanical method, such as cau- 

 tiously brushing the section with a camel's hair brush, or by digestion. 



183. Digestion Method. The organ to be examined (e. g., 

 lymphatic node, spleen, etc.), is preserved in 67% alcohol, cut into 

 sections 2 mm. or more in thickness, washed thoroughly in water to 

 remove the alcohol, and digested with pancreatic solution in 1% 



