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. 2010 Jul 20;32(3):184–196. doi: 10.1159/000313902

Fig. 3.

Fig. 3

BDNF attracts geniculate neurites during intralingual pathfinding and initial targeting. af E15 geniculate explants. Control beads (Cn) do not bias E15 geniculate neurite outgrowth promoted by 100 ng/ml BDNF (a), but BDNF beads (BD) profoundly bias outgrowth (b). Note that the distant ganglion (on the left) has proximal outgrowth, even though it is further from the bead than the distal side of the other ganglion, which has no outgrowth. c Attraction to BDNF beads is saturable using 100 ng/ml BDNF in the bath. d E15 neurites do not grow beyond BDNF beads. Dots indicate the perimeter of the right half of the bead. Note that the ganglion on the right extends several fascicles toward the bead, all of which are longer than the neurites contacting the bead from the other ganglion. This indicates that sufficient time was permitted for neurite extension beyond the bead. e Neurite fascicles that contact control beads can grow beyond the bead (arrowhead). f High concentrations of BDNF inhibit outgrowth: fewer or no neurite fascicles are observed when 200 ng/ml BDNF is provided in the presence of a BDNF bead than when 100 ng/ml BDNF is present (compare with c). gl E18 geniculate explants. g Neurite growth stimulated by 25 ng/ml BDNF is not biased by control beads. h Geniculate neurite outgrowth is strongly biased by BDNF-soaked beads. Note that neurites from the ganglion on the left are shorter than those from the ganglion on the right and they appear to stop prior to contacting the bead. As with E15 cultures, less outgrowth is observed when 200 ng/ml BDNF is provided in the bath (j) than when 100 ng/ml is provided in a BDNF bead culture (l). Neurites advance beyond a control bead in the presence of 100 ng/ml BDNF (k, arrowhead) but not a BDNF bead (l). mo In these P23 cultures, there is little difference in the length of proximal and distal outgrowth, regardless of whether a control bead (m) is used or a BDNF bead (n). o In this stop assay, neurites extend preferentially on the side of the ganglion with the BDNF bead (just above the ganglion), but many neurites extend beyond the bead. Promoting growth beyond the source of BDNF is consistent with a trophic influence. Calibration bar = 250 μm.