34 MORPHOLOGY OF THE FORMED ELEMENTS 



to affect the blood forming organs immature forms of leucocytes 

 may pass into the blood stream. In certain cases of leukemia not 

 only immature but even parent forms of leucocytes may be found 

 in the circulating blood. The immature leucocytes occur in the 

 circulating blood only in small numbers except in cases of leukemia. 

 It is important to recognize them when they do occur as their 

 presence indicates a serious condition, involvement of the blood 

 forming organs. It is sometimes difficult to distinguish immature 

 cells belonging to the myelocytic from those of the lymphocytic 

 series. The granules of the myelocytes usually do not stain well 

 with the ordinary blood stains. Graham recommends the use of 

 his alphanaphthol-pyronin method, by which myelocytic cells 

 are made easier to recognize as the granules are made prominent. 



Myelocytes are cells whose cell bodies contain fine or coarse 

 granules like those of polymorphonuclears or eosinophils. The 

 nucleus is rounded or may be indented. According as the granules 

 are fine or coarse the cells are known as finely granular myelocytes 

 (usually simply myelocytes) or eosinophilic myelocytes. The eo- 

 sinophilic myelocyte is found in the circulating blood practically 

 only in cases of mixed celled leukemia. 



Metamyelocytes or transitional leucocytes are intermediate 

 between myelocytes and polymorphonuclears. The nucleus in- 

 stead of being round or oval as in a myelocyte is bent or twisted. 

 It differs from a polymorphonuclear in that the nucleus does not 

 consist of lobes connected by slender portions or of separate divi- 

 sions. 



Metamyelocytes and myelocytes are sometimes found in small 

 numbers in the circulating blood in severe cases of infection or 

 intoxication. Large numbers of myelocytes and metamyelocytes 

 are found in the circulating blood in cases of mixed celled leukemia. 



The leucoblast is a still more primitive type of cell. Its neuclus 

 is like that of a myelocyte, but the cell body is feebly basophile 

 and is without the granules that distinguish the myelocytes, 

 metamyelocytes and polymorphonuclears. Lcucoblasts closely 

 resemble large lymphocytes. They are found in cases of acute 

 mixed celled leukemia. So far as I know lcucoblasts have not 

 been recognized in the circulating blood of the domesticated 

 animals. 



Plasma cells (reizungsformen, Turk) are non-granular, mono- 



