Distribution of extravasated serum protein after cryoinjury in neonatal and adult rat brains

The sequelae of cryoinjury to unilateral cerebral cortex were compared in neonatal and adult rats. In neonatal rats, immunostaining for autologous albumin disclosed a wide spread of extravasated albumin in both hemispheres on day 1 and rapid clearance from the tissue by day 7, whereas in adults rats, the distribution of albumin had progressively increased by day 7 and was then restricted to the injury site by day 14. Horseradish peroxidase tracing revealed a leakage of serum proteins by day 3 in neonates and by day 7 in adults. The rapid clearance of serum proteins from the neonatal brain tissue appeared to be promoted by vimentin-positive radial glia in the subpial and periventricular regions. A possible causal relationship between the rapid clearance of serum proteins and unique outcome of the cryoinjury in the neonatal brain is discussed.