Abstract: Objective To develop a method of location of prenatal female mouse reproductive tract based on paraffin block serial sections of female fetuses, and get high quality paraffin sections of fetuses containing female reproductive tract (FRT).And to investigate the role of Wnt5a during the development of FRT of prenatal mice. Methods The sex of fetuses at gravidity 155 days( G15.5d), G17.5d, G19.5d) and G21.5d was identified by polymerase chain reaction(PCR),and the female fetuses were embedded in paraffin block, the specimen was sectioned serially . One of every four sections was stained by hematoxylineosin(HE), and the next one being used laterThe images of specimen were taken with digital camera and the serial sections were obtained. The paramesonephric duct /uterus were located and recognized. Immunohistochemistry was used to determine the location and intensity of Wnt5a staining in the middle of the paramesonephric duct / uterus. Results The morphology of the paramesonephric duct /uterus was recognized first and the sections of fetuses with paramesonephric ducts were obtained. The intensity of Wnt5a immunohistochemical staining was increased from G155d to G215d in mesenchymal cells(EM>P/EM> <0.01). Conclusion Wnt5a plays a marked role in early period of female mouse reproductive tract, and is possible to

Key words: Fetus, Paramesonephric duct, Uterus, Paraffin section, Wnt5a, Immunohistochemistry, Mouse