ORIGIN OF MACROPHAGE IN THE TELENCEPHALIC WALL OF THE RAT FETUS ‐ AN OBSERVATION BASED ON METHYLAZOXYMETHANOL AND RADIATION INDUCED LESIONS

Abstract

Pregnant rats in the 15th day of gestation received an injection of methylazoxymethanol 20 mg/kg and were exposed to 200 r. of Co60. Fetuses were examined at various time intervals up to the 22nd day of gestation. Widespread necrosis throughout the dorso‐lateral wall of the telencephalon appeared early. At a subsequent stage frequently observed in the ventricular zone was necrotic cell debris in the ventricular columnar cells and macrophages. The macrophages migrated outwards and eventually digested their content to lipid droplets and transformation to an elongated cell with branching processes was traced. Vacuolated amoeboid cells first described electron microscopically by Caley and Maxwell in the neonatal rat cerebrum, appeared in later fetal life in untreated control animals and increased in treated animals. Additional to pinocytosis their phagocytic activity was enhanced and ultimate digestion of their content to lipid droplets was observed. Although the fate of the macrophage was not ascertained, their ectodermal origin was discussed.