Abstract

Recently serial experimental studies on the transformations of reticular cells into plasma cells were reported by co-workers in our department. They confirmed histologically the transformation in the thymus from irradiated rats; in the spleen and lymph node from adrenalectomized rats and treated with cortisone or DOCA; in the transplanted spleen; and also autoradiographically in the spleen and the lymph node from the rats treated with cortisone, DOCA or from adrenalectomized rats. It is a well known fact that the plasma cell is most easily differentiated from the lymphocyte by the characteristic feature that is richness of rER in the cytoplasm. Thus the author applied electron microscopy to this study. Materials find Methods ; Albino male rats, weighing approximately 200 gms, were used. The transplantation of the spleen were performed by the Cameron and de Saram method. The experimental rats were divided into 10 groups. The transplanted spleen were histologically (H & E, methyl green pyronin, van Gisson) and electron-microscopically observed.
Results
; Within 3 days implanted spleen fragments became almost completely necrotic but splenic capsule, trabecauae and reticular tissues were remained. The beginning of regeneration usually started subcapsularly. At the 4th day the invasion of newly formed capillary accompanied with fibrous tissue appeared extracepsularly, and then appeared subcapsularly. The regenerative cells appeared at first in the subcapsular reticular tissue and they were characterized by round oval vesicular nuclei with abundant cytopiasm. These cells were localized in the subcapsular area forming cell clusters and were strong1y pyroninophilic and quite separated topographically from other leukocytes such as and small lymphocytes, neutrophils which were found around capillaries. These colonized cells had many mitochondria and rER in their cytoplasm, and were strongly indicative of young plasma cells. Such colonization was numerous and, with progress of regeneration, the same colonization of young plasma cells appeared in the newly formed splenic cord. In parallel with progress of regeneration, most cells became mature plasma cells. The cells in the colonization showed electron-microscopically successive transitional pattern from the reticular cells to young or mature plasma cells.
Conclusion
; In the autotransplanted spleen, it was confirmed light and electron-microscopically that the plasma cell arises from the reticular cell in the regenerative spleen.