Figure 1.

Preterm fetal cerebral blood flow (CBF) does not display gradients of flow under basal or ischemia-reperfusion conditions that is consistent with vascular border zones or endzones. (A) Quantification of regional fetal cerebral blood flow in vivo under conditions of basal flow. The top image in panel A represents a 3-D surface reconstruction of fluorescence images of a 0.65 gestation control ovine brain that indicates the frontal and parietal levels to which the lower blood flow images correspond in 1 and 2. Representative pseudocolor scale basal flow images show higher blood flow (arrows) in the pons (image 1) and sub-cortical gray matter (image 2) and lower flow (dark blue) in the periventricular white matter (arrowheads). (B) The fetal cerebral white matter was segmented into medial and lateral sections, both of which were further segmented into inferior, middle, and superior regions. No differences were found between basal CBF values in medial and lateral white matter. (C) Basal CBF values (mean ± SEM) for the entire inferior, middle and superior PVWM. No differences in CBF were seen between superior and inferior regions of cerebral white matter, which supported a lack of gradients of CBF during basal or ischemia-reperfusion conditions. Adapted from Riddle A, Luo N, Manese M, et al. Spatial heterogeneity in oligodendrocyte lineage maturation and not cerebral blood flow predicts fetal ovine periventricular white matter injury. J Neurosci. 2006;26:3045-55 and McClure M, Riddle A, Manese M, et al. Cerebral blood flow heterogeneity in preterm sheep: lack of physiological support for vascular boundary zones in fetal cerebral white matter. J Cereb Blood Flow Metab. 2008;28(5):995-1008 with permission.