Immunofluorescent analysis
Paraffin sections (5μm) of placentas were rehydrated and incubated in sodium citrate buffer (pH 6.0) for 10min to retrieve antigens. After blocking in 3% H2O2, the slides were incubated with antibody against laminin (1:200; Abcam, Cat# ab11575; RRID: AB_298179) at 4°C overnight. After washing 3 times with PBS, the sections were incubated with Alexa fluor 488 donkey anti-mouse IgG(H+L) (1:1,000 dilution) for 2h in dark at room temperature. Then the slides were mounted with cover glass by mounting solution, and the picture was taken under Zeiss LSM 780 confocal microscope (Carl Zeiss Inc., Jena, Germany).