CELL RESTS IN THE REGION OF THE FOURTH VENTRICLE

Abstract

CELL RESTS in the region of the fourth ventricle are found most frequently in fetuses and premature and stillborn infants.¹ The frequencies of occurrence of rests after birth are relatively the same in the three groups. Cell rests are found predominantly in the ponticulus of the medulla oblongata and the nodulus of the cerebellum. The cerebellar white matter is the next most frequent site of cell rests, while the anterior, posterior, and inferior medullary vela are involved less frequently. When studied histologically, cell rests show variation in cellular composition, in the degree of cellular differentiation, and in the degree of organization. Brun,² in reporting the results of his study of malformations of the cerebellum in 1917 and 1918, pointed out that cellular elements which are dislocated from their normal position and which have no recognizable architectural pattern should be designated as "heterotaxic," while the term "heterotopic" should be