本文对3例低分化滑膜肉瘤的组织形态及超微结构作了系统描述。提出该肿瘤细胞虽在其排列上有相似上皮的表现,但并非真正上皮。其细胞形态与滑膜被复细胞相似且兼有A、B型细胞的特点,并有类分泌现象。故推测滑膜肉瘤可能为一由特化的间叶细胞产生的恶性肿瘤,它以有上皮样排列和类分泌现象为其特点。 This article systematically described the histomorphology and ultrastructure of three cases of poorly differentiated synovial sarcoma. It is suggested that although the tumor cells have similar epithelial appearance in their arrangement, they are not really epithelial. The cell morphology is similar to that of synovial cells, and has the characteristics of both A and B cells, and has a class secretory phenomenon. Therefore, it is speculated that synovial sarcoma may be a malignant tumor produced by specialized mesenchymal cells, which is characterized by epithelial-like arrangement and secretion-like phenomenon.