Sidney Klein 323 



To demonstrate prozymogen as basal filaments or as a diffuse chromo- 

 phile substance in the base of the cell toluidene blue was employed in 

 saturated aqueous solution. Better results, however, were obtained by 

 a method devised by Bensley of staining in toluidene blue, orange G, and 

 acid rubin. This method is as follows : the sections cut as thin as possible 

 in paraffin and fastened to the slide by the water method are passed 

 through benzole, absolute alcohol, and graded alcohols, to water. They are 

 then stained for a period of one minute with a mixture containing equal 

 parts of the saturated aqueous solutions of Orange G, and acid rubin. 

 Then wash in water and stain for one minute in saturated aqueous solu- 

 tion of toluidene blue. Wash in water; transfer to absolute alcohol; 

 clear in benzole, and mount in balsam. The result as far as the distri- 

 bution of the toluidene blue is concerned is much the same as that ob- 

 tained by staining with this dye alone. The intensity of the blue stain, 

 however, is much increased, and in addition the method offers the ad- 

 vantage of the contrast stain produced by the rubin and orange. By this 

 method chromatin and prozymogen (or basal filaments) are stained 

 intensely blue, protoplasm faint bluish, zymogen granules red, and the 

 contents of goblet cells remain unstained. 



Confirmatory evidence of the presence of prozymogen in the Paneth 

 cells was sought by means of the microchemical reaction for organic iron 

 introduced by Macallum. 



In the guinea pig Paneth cells are very abundant in the glands of 

 Lieberkiihn of the small intestine. They occupy chiefly the deep ends 

 of the gland where they often form a continuous layer which is inter- 

 rupted by comparatively few goblet cells. A few also occur on the sides 

 of the gland but the upper ends of the glands are wholly free from them. 



The structure of these cells depends on the stage of physological 

 activity. In the animals which are kept constantly supplied with food 

 of which they are allowed to partake at will, the cells are cylindrical in 

 shape, the outer end being somewhat broader than that which is directed 

 towards the lumen. In each cell two zones of about equal width are 

 easily recognized. The distal zone directed towards the lumen of the 

 gland is occupied by fine granules which are so closely crowded that it 

 is often difficult to recognize the thin laminae of cell-protoplasm which 

 separate them from one another. In material fixed in aqueous sublimate, 

 however, many cells may be found from which the granules have been 

 removed and here we find the distal zone occupied by a fine meshwork 

 which corresponds in the size of its spaces to that of the granules, indi- 

 cating that each granule occupies a small space in the protoplasm, a thin 

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