目的　探讨胎儿房室结内的细胞类型和大小。　方法　石蜡切片 ,H E染色 ,光镜观察胎儿心脏房室结的细胞形态、类型 ;采用HIPAS 10 0 0图像分析仪对其进行定量分析。　结果　胎儿房室结的细胞主要为亮细胞、暗细胞和移行细胞。亮细胞和暗细胞为纺锤形或椭圆形 ,少数多边形 ;移行细胞细短柱形。亮细胞和移行细胞的细胞核明显大于暗细胞。　结论　胎儿房室结的起搏细胞包括亮细胞和暗细胞 ,它们可能是一种细胞的不同功能状态 Objective To investigate the cell type and size in fetal atrioventricular node. Methods Paraffin sections were stained with H E and the cell morphology and type of fetal atrioventricular node were observed with light microscope. Quantitative analysis was performed by HIPAS image analyzer. Results Fetal atrioventricular node cells mainly bright, dark cells and transitional cells. Bright cells and dark cells are spindle-shaped or oval, a few polygons; migrating cells thin cylindrical. Bright and migratory cells have significantly larger nuclei than dark cells. Conclusions Pacing pacemaker cells in fetal atrioventricular node include bright and dark cells, which may be different states of a cell