The fine structure of the reticulum cells in lymph‐nodes from cyclophosphamide‐treated thymectomised mice

In mice depleted of lymphocytes by thymectomy and cyclophosphamide treatment the popliteal lymph nodes showed macrophages, fibroblasts, endothelial cells and a heterogeneous group of cells here described as reticulum cells. Some of these both within and outside the germinal centres had fine long processes, i.e., were dendritic, and some had deep cytoplasmic invagination. Interdigitating cells were not a feature of the nodes and there was little evidence of migration of cells through post-capillary venules.