Lymph nodes of the N:NIH(S)II-nu/nu mouse.

In N:NIH(S)II-nu/nu mice, which express the nu and the Xid genes, T and B lymphocytes are deleted. We studied their lymph nodes in the light of new knowledge of the morphology of the nodes of normal and athymic animals. Histologic preparations of the nodes from various anatomical sites were analyzed in 9-week-old mice. Node sections were also stained for IgM or IgG. The study revealed that, the frameworks of the peripheral cortex, the deep cortex, and the medulla were developed in these nodes, although they were quite devoid of lymphocytes or plasmocytes. However, the outermost (or subsinus) layer of the peripheral cortex of some nodes was populated with lymphocytes. In some cervical nodes, a few follicles, lymphocyte clusters, and a well-developed plasmocyte population were also present. The lymphocytes of the subsinus layer and the clusters were B cells with an increased expression of IgM. The modifications of these nodes are discussed on the basis of recently developed concepts of node functioning.