Figure 3.

Diffusion of different sized rhodamine labeled biotinylated dextrans (BDA) into postnatal mouse brain. Vibratome coronal sections (80 μm thick) through cortex of mice injected with different sized BDAs (3, 10, and 70 kDa). Markers were injected into the contralateral ventricle and left to diffuse for 2–3 min at E19 and P0, 5 min at P10 and 10 min in the adult. Note that none of the dextrans entered the brain at E19. In older brains there was a progressive increase in penetration depending on the size of the dextran. By adulthood all three dextrans were entering the brain to a similar extent. Apparent diffusion distances shown in Figure 4. Distribution of BED (286 Da) is illustrated in Figure 2 for comparison. E, embryonic day; P, postnatal day. Scale bar 500 μm.