Organization of ruminant Peyer's patches as seen with enzyme histochemical markers of stromal and accessory cells.

Five enzyme histochemical reactions were used to characterize calf, goat kid and lamb Peyer's patches. 5'-nucleotidase and acid phosphatase gave a reticular pattern of staining in follicular and interfollicular regions, respectively. Different subpopulations of fibroblastic reticulum cells were suggested for the T cell area, the dome/corona region, and the follicle capsule. The T cell area and the neck portion of the follicle showed a positive reticular reaction with alkaline phosphatase and non-specific esterase. Follicular dendritic cells were positive for Mg2(+)-ATPase in the follicle centre, contrasting with a negative reaction in the periphery. Dendritic cells prevalent in the dome and T cell area showed a Mg2(+)-ATPase reactivity. Macrophages were stained with non-specific esterase and acid phosphatase. No principal differences were found in cell populations between the three species or between fetuses in late gestation and postnatal animals, although the size of the respective compartments varied.