Cytokinetics of antibody formation

Abstract

The mediastinal nodes of untreated rats contain medullary cords populated by variously matured plasmocytes, classified into large, medium, and small on the basis of nuclear diameters. Since hemocytopoietic cells proliferate while maturing and since proliferation yields progressively greater numbers of mitoses, it follows that the order of mitotic increment of the variously matured plasmocytes can tell the position of each type in the plasmocytic series. Counts were carried out in 32 rats killed at four successive 6-hour intervals. For 3000 plasmocytes counted per rat, there was an average of 10, 26, and 34 mitoses of large, medium, and small plasmocytes respectively. On the basis of an equal mitotic duration for all plasmocytes, this indicated that the large plasmocytes yield the medium plasmocytes which, in turn, give rise to the small plasmocytes. The number of generations of each type of plasmocyte was determined by comparing the experimental ratios, for number of mitoses of a progeny type of plasmocyte over that of its progenitor type, with similar theoretical ratios expected for variable numbers of generations of progeny and progenitor cells. Comparisons indicated that there are likely four generations of large plasmocytes followed by two of medium plasmocytes and also two of small plasmocytes. As for the nature of the ultimate precursors of the large plasmocytes, it is postulated that they are the hypertrophied endothelial cells of the nodes' postcapillary venules. These cells would receive the appropriate stimulus for plasmocytic differentiation from the small lymphocytes which cross them to enter these venules. Present termsCurrent Nuclear terms diameters ~~ P

Primitive Erythropoiesis in Early Chick Embryogenesis

“…Similar studies showed that uridine incorporation is reduced to less than 10 0/0 of the 5 day level, while leucine incorporation diminished much less markedly. This is similar to the pattern of macromolecular synthesis seen in other erythropoietic systems (Grasso and Woodard, 1965, 1966, 1967Kovach et al ., 1967 ;de la Chapelle et al ., 1969) . Our analysis will deal only with the primitive line of red cells .…”

Surface Alloantigens of Plasma Cells

“…The cell which gives rise to the plasma cell is not absolutely identified. Four contenders theft have been considered are lymphatic reticular cells (19 21), lymphocytes (22)(23)(24), endothelial cells in the postcapillary venules of lymphatic tissue (25), and perivascular mesenchymal cells (26). The ancestral cell, not necessarily the immediate parent cell, is assumed to be a mobile cell of the bone marrow, for imnmnoglobulins of allogeneic radiation chimeras are of the donor type (27).…”