AN OBSERVATION OF THE ULTRAMICROSCOPIC STRUCTURES OF GIANT CELL TUMOR OF BONE

The ultramicroscopic structures of bioptic materials of three cases of giant cell tumor of bone were studied with the purpose of furnishing more data to bear upon the following problems:Firstly,what are the special features and characteristic behaviors of the stromal as well as the multinucleated giant cells? Secondly,what are the relationships of the above memtioued two kinds of cells as.well as those of the different types of.stromal cells? And lastly,how are the multinucleated giant cells originated from the uninucleated stromal cells?It was found that the ultramicroseopic structures of the uninucleated stromal cell as well as the multinucleated giant cells had shown respectively their special features and characteristic behaviors in differentiation and degeneration.Basing upon the special features and behaviors,the stromal cell could be subdivided generally into Ⅰ,Ⅱ and Ⅲ three main types,among which owing to the presence of Ⅱ to Ⅲ transitional types,we were inclined to consider type Ⅱ and Ⅲ stromal cells as two different stages of degeneration of one type.But whether or not type Ⅱ stromal cells might be differentiated into other types of cells is a problem remained to be studied.As to the interrelationship between the stromal and multinueleated giant cells,normal physiological histological studies informed us that these two kinds of cells were all originated by cell multification from the primitive mesenchymal cells,which often appeared to be syncytial in some parts of the cells.If the physiological histology could be considered as the basis and starting point of the pathological histology,it might be conceivable that the uninueleated stromal cells and the multinucleated giant cells both had a common origin and further more in their course of differention might be intertransformed.In the study of the physiological histology,there were facts to show that the multinucleated giant osteoclasts could undergo self-separation from the multinucleated giant cells to become uhimicleated stromal cells or osteoblasts.Under the pathological conditions,it was quite-possible for a number of uninucleated stromal cell to fuse together to form multinucleated giant cells.But from the limited observation of our materials,no indication of such fusion was found.Quite on the contrary,there were indications that a multinucleated giant cell was undergoing self-separation to become type I stromal cells. Again,in our materials,it was found a certain number of double nucleated cells,in which the two nuclei often arranged themselves in a lock and key fushion.It appeared,therefore,that these cells were formed by a nuclear division without accompanied by cell division.If such a process was being carried on (for which no evidence had been yet obtained).,we would be led to believe the possibility that mul-tinucleated giant cells were originated from the nuclear divisions without cytoplasmic divisions of the stromal cells ought not be completely eliminated from our consideration