Paracortical post-capillary venules of human lymph nodes with special reference to the distribution of their endothelial IgG.

The distribution of IgG in the endothelium of the paracortical post-capillary venules (PCV) of human lymph nodes was studied in frozen sections by using an indirect immunoperoxidase technique. Three different patterns of distribution could be differentiated (luminal site, intraendothelial and basement membrane site). Each of these patterns was characteristically encoutered in association with one of three grades of PCV (graded on the basis of the height of their endothelial cells). The significance of this close relationship between the IgG distribution and the changes in PCV endothelium was discussed in regard to the T-lymphocyte recirculation. A hypothesis was introduced describing the possible sequence of events involved in the traversing of T-lymphocyte through the PCV endothelium.