Figure 3

Acute maternal periconceptional TCDD exposure induces nuclear and cytoskeletal defects in compaction stage pre-implantation embryos. Compaction stage pre-implantation embryos collected from control and acutely exposed (50 ng/kg and 1 μg/kg TCDD) female rats and processed for visualization of microtubules, f-actin and DNA by confocal microscopy. (A-C) Control 8-cell pre-implantation embryo. (D-F) 50 ng/kg TCDD exposed 8-cell pre-implantation embryo with monopolar spindle (D, arrow) and f-actin cortical localization (F, arrow). (G-I) 1 μg/kg TCDD exposed 8-cell pre-implantation embryo with distorted overall shape and centrally localized nuclei (H, arrows). (J-L) 1 μg/kg TCDD exposed 8-cell pre-implantation embryo with global defects in the microtubule and f-actin networks; note micronuclei (K, arrow). Relative fluorescent intensity profiles for a normal bipolar spindle from a control pre-implantation embryo (M) and a monopolar spindle from a 50 ng/kg TCDD exposed pre-implantation embryo (N) are shown. Note the absence of tubulin (green) fluorescence on the basal side of the aligned chromosomes (blue) and the intense f-actin (red) signal at the apical cortex compared to the basal cortex (N). This is a different embryo to that shown in D-F. Scale bar: 15 μm.