LEUCOCYTES 15 



Classification 



The following different kinds of leucocytes are described. 



1. Polymorphonuclear Cells.- — In size 10-12/<. The 

 nucleus varies considerably in shape, being usually either 

 three-lobed or horse-shoe. The cell-body contains fine 

 granules, which stain, some with acid, others with basic 

 dyes, the result on double staining giving a purple effect. 

 Hence the name neutrophile sometimes given to them. 

 These cells are actively amoeboid. They constitute 60-70 

 per cent, of the total leucocytes. 



2. Coarsely-granular or Eosinophile Cells.- — In size and 

 in the shape of the nucleus, these resemble the polymorpho- 

 nuclear cells. They differ from them in containing coarse 

 granules, which stain deeply with eosin. They are only 

 found to the extent of 1 per cent. 



3. Lymphocytes. — These are smaller than the above 

 varieties, having a diameter of 7-5. The cell is spherical 

 and is almost filled with the nucleus, which is often kidney- 

 shaped. The cytoplasm stains a pale blue, and is free 

 from granules. Occasionally large forms are seen. These 

 cells are not amoeboid. About 25 per cent, of the leucocytes 

 are of this class. 



4. Mononuclear or Hyaline Cells. — These are large— up 

 to 25/<, and round or ovoid in shape. The nucleus is ill- 

 defined and feebly staining. The cell-body is shghtly 

 basophile and non-granular. The cells are slightly amoeboid. 

 These form about 2 per cent, of the leucocytes. 



5. Basophile or " Mast " Cells. — In size they are about 

 10/<. The nucleus is tri-lobed, and the cell-body contains 

 basophile granules. They are difficult to find, forming 

 less than 1 per cent. 



Origin of the Leucocytes 



The polymorphonuclear cells and probably the eosino- 

 philes are formed in the bone-marrow from large cells 

 known as myelocytes. The lymphocytes are formed in 



