Fig. 3

Neuronal progenitors undergo apoptosis in both the head and spinal cord of eftud2^fn10a mutants. Immunostaining and TUNEL staining in cryosections of the embryonic brain (A–L, A'–L') and spinal cord (M–T, M'–T') at 36 and 48 hpf. (A–D, A'–D') The neural progenitor marker Sox2 was co-localized with apoptotic (TUNEL⁺) cells in fn10a mutants (B, B', D, D'). Panels A' to D' are expanded from the boxed areas in panels (A to D). Apoptotic cells were hardly detectable in wild-type siblings (A, A', C, C'). (E–H, E'–H') The postmitotic neuronal marker Huc at 36 hpf was not co-localized (F, F'), but was partially co-localized at 48 hpf (H, H') with apoptotic cells in fn10a mutants. (I–L, I'-L') The mitotic-phase marker pH3 was barely co-localized with apoptotic cells in fn10a mutants at 36 hpf and 48 hpf. Note that the number of pH3⁺ cells was dramatically higher in fn10a mutants at 48 hpf (L, L') than at 36 hpf (J, J'). (M–N') The neuronal precursor marker sox2 was co-localized with apoptotic cells in the spinal cord in fn10a mutants. Note more TUNEL-positive cells in fn10a mutants (M', N'). (O–P') Immunostaining revealed the disruption of neural-glial cell formation with more TUNEL-positive cells in fn10a mutants (O', P') than in sibling controls (O, P). (Q–R') Newly-generated Huc⁺ neurons were less affected in fn10a mutants at 36 hpf (Q'), but they underwent apoptosis at 48 hpf (R'). (S–T', U–V') The mitotic-phase marker pH3 was increased in fn10a mutants at 48 hpf and partially overlapped with apoptotic cells (S', T'). (M–T') Transverse views; (U–V') sagittal views. Scale bars in A–D, E–L', 50 μm; A'–D', M–T', 10 μm; U–V', 30 μm; n ≥ 5 for each panel.