Development of the thymus and Peyer's patches in the first year of life in red deer (Cervus elaphus).

In young ruminants, as in most animals, the thymus and Peyer's patches (PP) play a key role in immune function. In sheep and cattle it has been shown that they follow a recognisable pattern of development throughout early life but a study of these tissues in red deer (Cervus elaphus) had not been previously conducted. Red deer are undergoing increasing domestication thus it was important to determine whether there were any significant differences between species. Samples from the thymus, jejunal PP and ileal PP were obtained from deer at 1, 1.5, 2, 3, 6, 9 and 12 months of age. Tissues were measured, processed and comparisons between the equivalent tissues in cattle and sheep were made. The thymus and Peyer's patches of red deer were observed to follow similar patterns of development and involution as in other ruminant species. The thymus was also observed to show a seasonal decrease in weight and cellular composition possibly due to nutritional and environmental stresses. Moreover, evidence for the prevailing idea that the ileal PP acts as primary lymphoid tissue in ruminants was obtained.