The origin of the dendritic reticulum cell

Abstract

To obtain more information concerning the origin of dendritic reticulum cells, the development of germinal centers in the spleens of rabbits was investigated by conventional light microscopy, enzyme histochemistry, and electron microscopy. Washed sheep erythrocytes were used as antigen. Splenic tissue was examined on the 13th, 18th, 21st, 27th and 48th day after antigen administration. Electron microscopic investigations revealed transitional forms between typical fibroblastic reticulum cells, which formed the framework of the entire splenic white pulp, and typical dendritic reticulum cells. During this transformation, the enzyme histochemical pattern of alkaline phosphatase disappeared and a positive alpha-naphthylacetate esterase reaction appeared in the transformed cells. On the basis of these findings, it is highly likely that dendritic reticulum cells develop through transformation of fibroblastic reticulum cells during the development of germinal centers in rabbit spleens. The characteristic folding of the surface membrane of dendritic reticulum cells is probably caused by the conspicuous increase in size of the Golgi apparatus, the detachment of vesicles, and the uptake of such vesicles by the cell membrane observed electron microscopically during the cellular transformation. Receptors that are of significance in antigen trapping might reach the cell surface in this manner, i.e., with the Golgi vesicles.

Scanning and Transmission Electron-Microscopic Studies on the Lingual Tonsil of the Buffalo (Bubalus bubalis)

“…Moreover, stellate shaped follicular dendritic cells (FDC) with delicate branching cytoplasmic processes and a few macrophages and plasma cells also observed in the buffalo calf [6] and horse [1]. FDC developed through the transformation of fibroblastic reticulum cells during germinal centre formation [13]. However, the desmosomal attachment of their processes suggested an epithelial rather than mesenchymal origin.…”

Lymphotoxin α/β and Tumor Necrosis Factor Are Required for Stromal Cell Expression of Homing Chemokines in B and T Cell Areas of the Spleen

“…The deficiency of FDCs in LT- and TNF-deficient mice has been well characterized ( 1 ). Ultrastructural studies have demonstrated that FDCs are part of a broader network of follicular stromal cells ( 55 ), and using the molecule BP-3 as a marker it has been possible to show that this more extensive stromal cell network is also LT and TNF dependent (see Fig. 3 ).…”