[Cardiac myxoma. Ultrastructural study of 2 cases].

From amongst a series of eight cardiac myxomas, two were studied by electron microscopy, which enabled us to identify, amongst varous cell types, two main ones. One of these was a secretory cell with Golgi apparatus and secretory vacuoles, and the other was of the expected type, with microfilaments showing signs of progressive differentiation towards either muscle or epithelial structure. A morphological picture of this sort tends to lend support to the concept of a dysgenetic origin for these tumours, arising from pluripotent embryonic cells sequestrated in the region of the fossa ovalis.