Fig. 4

Bisphenol A influences brain development in the prim-5 stage.

The expression patterns of markers in different brain regions (krox20, eng2b, and otx2) at the prim-5 stage are shown. The expression of krox20, a marker of rhombomeres 3 and 5, dorsal view (A,B). Abnormal patterning of rhombomeres 3 and 5 (black asterisk) was found in BPA-exposed embryos (B), which indicates that regionalization was affected. The patterns of eng2b expression indicated that the mid-hindbrain boundary (mhb) was minimized in the BPA-exposed embryos (red asterisk). Compared to the controls (C), BPA-exposed embryos showed a smaller mhb (D), lateral view; magnified views of the dorsal region are shown in the inserts at the right bottom corner. otx2 expression pattern was restricted in the BPA-exposed embryos (blue asterisk). Compared to the controls (E), the BPA-exposed embryos (F) showed reduced size of the midbrain. Magnified views of the dorsal section are shown in the corner. mb, midbrain; mhb, mid-hindbrain boundary; r3/r5, rhombomere 3/5. All were head to the left. Scale bars: 100μm (A,B); 125μm (C–F). The number of embryos with the presented phenotype is shown in the top right corner of the panel.