Аннотация:Abstract Corticosterone (1 μg/g) was administered to the pregnant rat mother at 17, 18 and 19 days of gestation. The pups were killed at birth or at 6 or 12 days of age and the morphological and biochemical development of the brain, with special emphasis in the cerebellum was studied. The brain and cerebellar weight was slightly diminished in the corticosterone treated animals. Corticosterone produced changes in the pattern of development of the cerebellar layers, causing an accelerated decrement of the external granular layer at 12 days of life. The total protein content of the cerebellum was increased in the hormone treated pups at birth, 6 and 12 postnatal days. Newborn corticosterone treated animals showed a decreased DNA content, but this phenomenon was completely reversed at 12 days. It was concluded that corticosterone given to the pregnant mother influences the time pattern of the development of the brain and the cerebellum.