AIM: To study the mo rphology and ontogeny of dend ritic celIs of Peyer's patches in rats at dlfferent development periods. METHoDS: The mo rphometric and flow cytometric analyses were performed to detect a the parameters of villous-crypts axis and the number of OX62+DC, OX62+CD4+SIRP+DC,and OX62+CD4 SIRP DC in the small intestine in different g roups of rats. The relationship between the Darameters of villous-axis and the number of DC and DC subtype were analyzed. RESULTS: All mo rPhometric Parameters changed significantly with the develoPment of PuPs in the diffe rent age g roups(F=10.751, 12.374, 16.527, 5.291, 3.486; P=0.000, 0.000, 0.000, 0.001, 0.015). Villous height levels were unstable and increased from 115.24μm to 140.43μm as ea rly as 3 wk postpartum. Villous a rea inc reased significantly between 5 and 7 wk postpa rtum. peeked uP t0 13817. 60μm2 at 7 wk postpa rtum. ViIious height and c rypt depth ratios were relatively stable and inc reased significantly from 2.80±1.01 to 4.54 4-1.56, 9-11 wk Dostpartum. TheexP ression of OX62+DC inc reased from 33.30%4-5.80%t0 80%±17.30%, 3-11 wk postpa rtum(F=5.536, P=0.0013). 0X62+CD4+SIRP+DC subset levels detected in single-cell suspensions of rat tota Peyer's patch dend ritic cells(PP-DCs)increased significantly from 30.73%±5.16%t0 35.50%±4.08%. 5-7 wk postpartum and from 34.20%±1.35% to 43.60%±2.07%9-11 wk postpa rtum(F=7.216, P=0.005). CoNCLUSIoN: This studY conf rms the age-related changes in villous-c rypt axis dlfferentiation in the sma intestine. Simultaneously,there a re also development and matu ration in rat PP-DCs phenotypic exp ression. Furthermo re, the mo rphologica changes of intestinal mucosa and the development of immune cells(especially DC)peaked at 9-11 wk postpa rtum, indicatina that the intestina mucosae reached a relatively mature state at 11 wk ostpa rtum.