Abstract
Tower and Herm 1 presented recently before the Society for Experimental Biology and Medicine some ideas concerning the origin of the mammalian (cat) and avian (chicken) blood cells. These authors were led by their observations on bone marrow in living cultures to the following conclusions:
1. The mammalian red blood corpuscle is a nuclear bud which escapes into the circulation as the true red cell.
2. The mammalian normoblast and the red corpuscle of the bird are the product of intranuclear activity and are phylogenetically identical.
3. Phagocytosis of red cells by the giant cells (megakaryocytes) in normal blood-forming tissues is by no means common. The true process is undoubtedly the manufacture of red cells and not the destruction of them.
My own observation of chicken bone marrow in living cultures led to some conclusions which are not in harmony with the quoted statement. I studied the bone marrow of chicken; therefore, my remarks are based only on observations on the bone marrow cells of this animal.
I could observe budding of red blood corpuscles after the first day of cultivation. Buds with and without nuclei appeared, also the rapid division of erythroblasts could be noted. The budding off of either small nucleated or non-nucleated cells cannot be a progressive process in the chicken because the avian red blood corpuscle is nucleated. Therefore the analogous observation of Tower and Herm with its conclusion that the mammalian red blood corpuscle is a nuclear bud which escapes into the circulation as the true red cell, loses its convincing power; probably the budding is a reaction of the normoblast to the change of its media, as it is also observed in amebae as soon as they are under unfavorable conditions and can be produced experimentally.
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