Fig. 7.

Immunofluorescence microscopy of the midbrain (superior colliculus) from E19–P1 Lmnb1^+/+ and Lmnb1^CS/CS embryos. (A) Low-magnification image of the Lmnb1^CS/CS midbrain showing that nuclei with naked chromatin are widespread. The region outlined in yellow is shown in B. (Scale bars, 20 µm.) (B and C) Higher-magnification images of Lmnb1^CS/CS and Lmnb1^+/+ midbrains. Sections were stained with antibodies against LAP2β (green) and lamin B1 (red); DNA was visualized with DAPI (white). Many neurons in Lmnb1^CS/CS mice were elongated with an asymmetric distribution of lamin B1 (arrows) and chromatin lacking a coat of lamin B1 (arrowheads). The LAP2β surrounding the naked chromatin was often distributed irregularly and sometimes had a honeycomb distribution. (Scale bars, 10 µm.) (D) Sections of the midbrain stained for lamin B2 (magenta). Lamin B2 was also distributed asymmetrically at one end of the nucleus (arrows). Arrowheads indicate naked chromatin. (Scale bars, 10 µm.)