[Ependyma of Merino sheep following continuous irradiation]

The ependyma of the lateral and IIIrd cerebral chamber was studied in 2 to 3 a old Merino sheep in the period of physiological anestrus after continuous 60Co irradiation for 7 d with a total exposure of 6.7 Gy. Locally focuslike or disseminated increased numbers of ependymous cells were found. Metaplasia of the original cell type was observed in the infundibular region of the IIIrd chamber, in the recessus pinealis and on the habenula in hyperplastic foci. The PAS-reaction for mucopolysaccharides in the subependyma at different sites of the lateral and IIIrd cerebral chamber was decreased to being negative. After continuous irradiation, the ependyma showed greater injury in the median and caudal than in the rostral portion of both chambers examined.