THE GONADS OF THE FOWL 97 



THE FATE OF THE GRANULOCYTES IN THE GONADS 



As stated above, the granulocytes so abundant in the gonads 

 of the embryo begin to disappear after hatching until they are 

 no longer found as important elements in the make-up of those 

 organs. The way in which this disappearance takes place has 

 some importance from the standpoint of hematology, for if it can 

 be proved that- most of the granulocj^toblasts enter the blood we 

 must regard the gonads of the embryo as transitory hematopoi- 

 etic organs, a function which has not been attributed to them. 

 A careful study of this problem showed that the vast majority of 

 the mature granulocytes either undergo disintegration or are 

 phagocytized by special elements and by the endothelial lining 

 of the blood-vessels. 



That the granulocytes enter the blood-stream is very difficult 

 to prove in the slides. Stages showing their migration through 

 the endothelium are extremely scarce and almost in every case 

 open to criticism. A careful study of the blood-vessels in the 

 vicinity of hematopoietic foci failed to show the occurrence of 

 granulocytes within their lumina in numbers large enough to 

 warrant the interpretation mentioned above. It might be argued 

 that this feature is due to the blood-current which sweeps away 

 the granulocytes as they enter the blood-vessels; but even taking 

 this into account, it is reasonable to expect that some of those 

 cells would be present in the smallest capillaries, where the blood 

 current is slower. 



Degeneration of granulocytes and their digestion by phagocytic 

 elements are common in the hematopoietic foci. The degener- 

 ated granulocytes are represented by elements somewhat smaller 

 than the normal cells of the same kind, containing a deeply stained, 

 much shrunken nucleus in which no definite structure can be 

 made out. The cytoplasmic granules are clumped and their 

 outlines are often difficult to detect (fig. 18, g). The cell finally 

 breaks up, setting free the granules, which may persist for a long 

 time scattered through the hematopoietic agglomeration. Extru- 

 sion of granules by either the granulocytoblasts or granulocytes 

 was never observed in the slides as a normal process. 



