Abstract
In normal salamanders (Triturus viridescens) thrombocytes are differentiated chiefly in the spleen. In splenectomized salamanders that were kept in excellent condition for one year after total extirpation of the spleen, thrombocytes were noted in all stages of development in the general circulation. The blood smears made from certain of these animals and stained with Wright's stain have afforded exceptionally favorable material for the study of thrombocytopoiesis.
The question of the origin of the thrombocytes has been at issue for many years. There is little unanimity of opinion concerning the type of cell from which the thrombocyte is derived, or whether its locus of differentiation is intra- or extra-vascular. Among the later investigators may be mentioned Sugiyama, 1 who holds that the thrombocyte is a derivative of the megaloblast, a hemoglobin-containing cell; Gordon, 2 that it is a senile erythrocyte; Maximow, 3 that it is a derivative of the lymphocyte; Hartmann, 4 that it is a cell genetically and structurally comparable to the megacaryocyte of mammals (as suggested by Wright 5 ) which furthermore differentiates in the bone marrow in extravascular location only; Jordan and Speidel, 6 that it is a derivative of the small lymphocyte which has a minimum of cytoplasm.
Our observations on splenectornized salamanders, however, point unmistakably to the large lymphoid hemoblast (hernocytoblast) as the ancestral cell. In our blood smears prepared according to Wright's technic, the young thrornboblasts are easily distinguishable from the young cells of the erythrocyte series. The thromboblasts present a characteristic reddish or reddish-violet fine granulation in the cytoplasm, quite different from the color shades of the proerythroblasts, the stages between the hemoblast phase and the true erythroblast.
Get full access to this article
View all access options for this article.