Morphology of the Extrafollicular Zone and Pseudo-Follicles of the Rat Lymph Node, and Their Role in Lymphocyte Traffic

Abstract

In a previous 3-dimensional study of the histology of the rat node (1,2), we reported that the small lymphocyte population of the cortex is mainly distributed into two morphologycally distinguishable components which we named: the extrafollicular zone and the pseudo-follicles. These lymphocytes are distinguished, on the other hand, into B and T cells which are said to be concentrated, respectively, in a B and T zone (paracortex) whose outlinings remain to be precised. An aim of further works was to complete the morphological study of the pseudo-follicles. Another objective was to attempt clarifying the topographical relation existing between the B and T zones, and the actual morphological structures which are the extrafollicular zone and the pseudo-follicles. A third goal was to determine the respective role of the latter two morphological components in the lymphocyte traffic within nodes.