Fig. 6.

Division and translocation of β- and α-tanycytes ex vivo. (A-D) Representative time-lapse images of lineage-traced Tom+ β-tanycytes (A-C) and α-tanycytes (D) in organotypic slice cultures. All images are derived from in vivo tamoxifen-pulsed P4/P5 brain, analyzed ex vivo starting at P7 or P12 for up to 96 h. (A) Cell division (red arrows) adjacent to 3V wall (dashed lines) in β1-tanycyte domain. (B) Delamination of an apical process from the ependymal wall and/or translocation of cell body towards the pial surface within β2-tanycytes domain (red arrow), resembling intra-kinetic nuclear migrations of embryonic ventricular zone cells. (C,C′) Ventro-dorsal translocation of a lineage-traced cell (cell ‘c’, red arrow) within the ventricular wall (C) and quantification of the distance travelled by cell ‘c’ away from cell ‘b’ (green line) towards cell ‘a’ (yellow line) (C′). Cell movement is not because of tissue shrinkage as the distance between cells ‘a’ and ‘b’ (blue line, ∼110 µm) remains relatively unchanged. Blue arrowheads indicate the position of cells ‘a’ and ‘b’. (D) Two independent cell division events by Tom+ α-tanycytes (red and green arrows). Note the asymmetry and subsequent lateral migration of daughters of these divisions into the neighbouring parenchyma. α, α-tanycyte; β1, β1-tanycyte; β2, β2-tanycyte; 3V, third ventricle; M.E., median eminence. See also Movie 1. Scale bars: 20 µm.