原来,在受精卵着床于子宫内膜之后,胚胎的部分胚膜和相邻的母体子宫内膜就会逐渐融合形成胎盘。胎盘与胚胎之间又会逐渐形成包裹着脐动脉、脐静
%B0%C4%C3%C5%B5%E7%D7%D3%C2%B7%B5%A5%2D%A1%BE%40%31%33%37%31%30%30%37%39%36%38%38%A1%BF
%B0%C4%C3%C5%B5%E7%D7%D3%C2%B7%B5%A5%2D%A1%BE%40%31%33%37%31%30%30%37%39%36%38%38%A1%BF
%B0%C4%C3%C5%B5%E7%D7%D3%C2%B7%B5%A5%2D%A1%BE%40%31%33%37%31%30%30%37%39%36%38%38%A1%BF
%B0%C4%C3%C5%B5%E7%D7%D3%C2%B7%B5%A5%2D%A1%BE%40%31%33%37%31%30%30%37%39%36%38%38%A1%BF




