Frequency of occurrence and distribution of the intra-epithelial lymphoid cells in the follicle-associated epithelium in phenotypically normal and athymic nude mice.

We have determined the number and pattern of spatial distribution of intraepithelial lymphoid cells in the follicle-associated epithelium of Peyer's patches and in the villus epithelium in the small intestine of athymic nu/nu mice and of the phenotypically normal mice kept in specified pathogen-free conditions. The results were obtained by histometric analysis of semithin histological sections. It has been found that the lymphoid cells were scattered randomly in the villus epithelium, while those in the follicle-associated epithelium were non-randomly distributed, occurring often in groups of several cells both for athymic nu/nu and phenotypically normal mice. The numbers of lymphoid cells in the follicle-associated and in the villus epithelium were found to be significantly lower in athymic nu/nu mice than in phenotypically normal mice kept in similar conditions. On the basis of the above results the proportions of thymus-dependent and thymus-independent lymphoid cells in the intestinal epithelium were deduced.