Hemokonia and Serum Granules 



Hemokonia, or blood dust (die English equiv- 

 alent), refers to the cell fragments, debris, and 

 minute bodies floating in the serum. Most of 

 these lie near the limits of microscopic visibility 

 When cell fragments are large they are called 

 plastids, but when small they are called hemo- 

 konia. 



Little has been written about cell debris. 

 Downey does not have "hemokonia," "blood 

 dust," or "serum granules" in the index of his 

 4-volume work on hematology. This is true for 

 some of the atlases on blood. Kracke and Car- 

 ver (1937) give one paragraph on the subject in 

 which they say (p. 107), "These particles do not 

 stain and their nature is unknown. They appear 

 similar in size to the granules in the cytoplasm 

 of granular leukocytes. This has led to the sup- 

 position that they are extruded granules but no 

 conclusive proof has been given for this identity." 



In avian blood occasional small fragments 

 from broken cells may be found. These are 

 chiefly heterophil rods or myelocyte rings and 

 granules. Their presence is due to the breaking 

 of cells that occurs when a smear is made. They 

 appear in practically any smear of bone marrow; 

 and recognizable rods from granulocytes, espe- 

 cially heterophils, can be found here and there 

 over most slides. Since granulocytes are so 

 much more abundant in bone marrow than in 

 circulating blood, it is not surprising that debris 

 of this sort is also more abundant. 



What should be included under the term 

 "hemokonia" has never been well defined; thus 

 it is not possible to decide whether serum gran- 

 ules should be included under the term. For 

 the present they are considered to be different 

 from hemokonia. They are found in great 

 abundance in the blood of birds. Usually they 

 do not take the stain but when they do, they pro- 

 duce a stippled mask over the cells (figs. 72 and 



322). Even when they do not stain, they can 

 be seen by reducing the diaphragm of the micro- 

 scope to increase the apparent refractility. In 

 embryo smears and in bone-marrow and thymus 

 smears of the embryo, they are especially abun- 

 dant (figs. 329 and 332). The typical appear- 

 ance is shown in figure 322. Among the serum 

 granules of this field are fragments of broken 

 cells also. Most low-power drawings from 

 hematopoietic organs of both adults and embryos 

 have been made without including the serum 

 granules. Cell identifications cannot be made 

 accurately where the granules lie on top of the 

 cells in large numbers. As may be seen in figure 

 322, the serum itself may take up the stain as 

 well as the granules in it. 



Two other granules should be mentioned — (1) 

 definite yolk granules found when blood is taken 

 from the early embryo at 48 to 72 hours, and 

 (2) chylomicrons, which Cage and Fish (1924) 

 descrilie. Yolk granules are larger than serum 

 granules and sometimes a whole yolk sphere is 

 seen. Yolk is not present in adult circulating 

 blood. 



Whether chylomicrons are present in birds has 

 never been determined. As the term was first 

 used it referred to the submicroscopic spheres 

 found in lacteal drainage from the small intestine 

 of mammals. It has a broader meaning than 

 this and in general refeis to lipid spheres found 

 in blood, chyle, or lymph. Dark field is re- 

 quired to see them. It would be interesting and 

 useful to determine whether chylomicrons of 

 mammals and serum granules of birds are the 

 same thing. There is considerable difference 

 in size, the serum granule being larger. 



The serums of pigeons and chickens are said 

 to contain a lipochrome pigment (Halliburton, 

 1886) that gives to them a color identical with 

 that found in fat cells of these birds. 



ADDENDUM 



The irregularity in the shape of erythrocyte 

 nuclei is described in the early part of chapter 2 



The cause is not 



and is illustrated in figure 29 



known, but Bessis (1956, fig. 195) photographed 

 similar irregularly shaped nuclei in chickens 

 after treatment with folic acid antagonists. 



93 



