The fine structure of chordoma with particular reference to the physaliphorous cell.

A chordoma was examined by electron microscopy. It was composed of stellate and physaliphorous cells. The fine structure of these cells is described. Transitional type cells are also described and it is suggested that the physaliphorous cells develop from the stellate cells through a process of vacuolation. Two types of vacuoles are described, ;smooth-walled' and ;villous' endowed with numerous structureless microvilli. Some observations on stained sections are discussed.