Embryonic pretreatment with bromodeoxyuridine blocks regeneration and functional recovery from perinatal medial frontal lesions in rats.

Removal of the midline frontal cortex on postnatal day 10 is followed by apparent regeneration of the part of the lost cortex, correlated with substantial recovery of function in adulthood. The spontaneous regrowth of the medial frontal cortex after midline frontal lesions on postnatal day 10 was blocked by pretreatment with bromodeoxyuridine (BrdU) on embryonic days 11, 12, 13, 15, or 17. BrdU pretreatment on embryonic day 21 or postnatal day 10 did not block either functional recovery or cortical regrowth. These results demonstrate a teratological effect of BrdU and are consistent with the claim that functional recovery after midline frontal removal on postnatal day 10 is supported by the generation of new midline frontal tissue.