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. 1999 Nov 29;147(5):1109–1122. doi: 10.1083/jcb.147.5.1109

Figure 4.

Figure 4

Exencephaly and neuronal ectopias develop in the anterior region of the forebrain. (A and B) Hematoxylin/eosin staining of sagittal brain sections from wild-type (A) and perlecan-null (B) E11.5 embryos. Note the extension and the thinning of the anterior part of the forebrain in the perlecan-null embryo (upper box in B). Ectopias are visible ventral of the medial ganglionic eminence (arrow) in the homozygous embryo. (C–F) Higher magnification of the lower boxes indicated in A and B. In a normal brain, the neuroepithelium and the underlying mesenchyme are separated by a BM (C) that contains laminin-1 (E). In the perlecan-null brain, the BM is discontinuous (D, arrow) and shows interrupted laminin-1 staining (F, arrow). (G and H) Higher magnification of the upper boxes indicated in A and B. In a normal brain, the neuroepithelium and the overlying mesenchyme are separated by a BM (G). In the perlecan-null brain, neuroepithelial cells have invaded the overlying ectoderm (H, arrow). (I–L) Immunohistochemical localization of nestin and β-tubulin type III in the neocortex of normal and perlecan-null embryos. The neocortex of the wild-type embryo contains nestin-positive cells (I) and a few β-tubulin type III–positive cells in the cortical subplate (K). Ectopic cells in the perlecan-null embryo are positive for nestin (J) but negative for β-tubulin type III (L). (M) Hematoxylin/eosin staining of the forebrain region of an E11.5 homozygote showing a defect in the ectoderm and a small hole of 5–10 μm (arrow). Note that the amniotic membrane is still intact (arrowhead). (N–Q) Nissl staining of coronal sections of wild-type (N and P) and perlecan-null (O and Q) E17.5 forebrain regions. The perlecan-null brain shows a ruffled surface, large ectopias, and abnormal lamination (O). Posterior to this area, the ruffles and defects in lamination are less severe (Q). Abbreviations: mz, marginal zone; cp, cortical plate; iz, intermediate zone; and vz, ventricular zone. Bars: (C–L) 125 μm; (M) 250 μm; and (N–Q) 500 μm.