Chicken Bone Marrow in Living Cultures. hi 



first been observed in the bone marrow by Foot 3, 4 and thought 

 by him in his first publication to be of mesenchymal origin and 

 in the second publication of lymphocytic origin. These "giant 

 cells" can be either changed fat cells or elongated vacuolized 

 connective tissue cells, or even enlarged myelocytes. They are 

 able to phagotize, to store fat, to divide into smaller forms — the 

 so-called cell culture type, small forms with nuclei, the chromatin 

 of which is arranged on a fine network. The formation of "giant 

 cells" characterizes the first period in the history of bone-marrow 

 in living cultures. After five or eight days, cultivation, the "giant 

 cells" have cleaned up the debris of the dying cells (blood cor- 

 puscles, fat cells, and large mononuclear lymphocytes). In the 

 second period the remaining cells adjust themselves to the con- 

 tinued life in tissue cultures. Cell types of the small lymphocyte 

 type with vesicular nuclei appear, which later are transformed 

 into different types of connective tissue cells — not exactly re- 

 sembling the connective tissue cells in the outgrown animal — but 

 closely resembling the mesenchymal cells of the embryo. 



The production of the cells of the second period can be 

 accelerated by washing the original bone marrow particle in 

 plasma. After the plasma has been renewed three or four times, 

 blood corpuscles and the lymphocytes which had been from the 

 beginning in the meshes of the bone marrow, have been left in 

 the media and only those cells close to the bone marrow network 

 are transferred to the new culture medium. In cultures prepared 

 in this way, we can observe small cells of lymphocytic character 

 which can store fat, phagotize and adopt all shapes of connective 

 tissue cells — but no formation of blood corpuscles or large mono- 

 nuclear lymphocytes can be observed. This proves clearly that 

 after the already preformed "ripe cells" are disposed of, no new 

 formation of blood corpuscles takes place in the living cultures. 

 It may be that the lack of oxygen prevents the appearance of red 

 blood corpuscles. The conditions in tissue cultures do not seem 

 to allow the stem cell to show its dualistic character. It does not 

 form blood corpuscles, but forms only the different elements of 

 connective tissue. 



•Foot, Beiir. z. path. Anal. u. z. allg. Path., 1912, Bd. 53, pp. 446-447. 

 4 Foot, Jour, of Exp. Med., 1913, Vol. XVII, pp. 44-60. 



