Abstract: BACKGROUND ＆ AIM: This study is to explore the dynamic trends of cell proliferation, apoptosis and the expression significance of involved genes as P21 and Ki-ras in developing intestines of mouse. MATERIAL ＆ METHODS: Intestine tissues were taken from different developmental phases of kunming mouse.Immunohistochemistry and TUNEL techniques were adopted to observe the variation of cell proliferation and apoptosis and the expression characteristics of P21 and Ki-ras were detected by in situ hybridization. RESULTS: We discovered that cell proliferation increased greatly in the 12th day while from the 13th to the 14th the proliferation maintained stead raise. With the development of embryo, the expressions of P21 and Ki-ras have a darker colour in the epidermic cell of intestines. CONCLUSION: Cell proliferation was accompanied by apoptosis during the development of mouse intestine.The dynamic changes of both ratios might be correlated to the different structures appearing in different developmental process.The possible function of P21 and Ki-ras might be correlated to the developmental process of middle embryo intestine.

Key words: cell proliferation, apoptosis, P21, Ki-ras, fetal intestine