IN VITRO CHARACTERISTICS OF A FOURTH VENTRICLE EPENDYMOMA MAINTAINED IN ORGAN CULTURE SYSTEMS: LIGHT AND ELECTRON MICROSCOPY OBSERVATIONS

Explants of a well-differentiated fourth ventricle ependymoma were grown on collagen-coated coverslips and in organ culture systems using gelatin sponge foam matrices and Millipore filter platforms. Viable explants were maintained on Millipore filter platforms up to 44 days and on sponge foam matrices up to 86 days. The structure of ependymal rosettes was well maintained throughout the period of study. By electron microscopy, additional features of differentiation were seen after 3 weeks, consisting of an increase in size and complexity of microrosettes, to which large numbers of cellular apical profiles contributed. Cilia with variable internal configurations were present. After 4 weeks there was frequent ependymal differentiation along the surface of the explants at their interface with the supporting matrix. Increased gliofibrillogenesis and glycogen rosettes were also evident after 3 weeks in culture. The explants were intensely positive when tested by immunofluorescence for the antigen of the glial fibrillary acidic protein. After 3 weeks in vitro , dense bands of basement membrane material forming complex intercellular finger-like projections became prominent.