Fig. 2. Cells derived from the hem fit the criteria of Cajal-Retzius cells. (A-C) From E10.5-12.5, hem-derived ß-gal-labeled cells (arrows) migrate into the MZ. (D,E) E18.5 cortical hemispheres in rostral (D) and lateral (E) views. ß-Gal-expressing cells cover the neocortex with rough boundaries at the olfactory bulbs and future rhinal sulcus (arrows). Caudally, some cells migrate below the latter boundary (asterisk). (F,G) p73 immunofluorescence in cells of the hem, the cpx and the MZ of the hippocampal (F) and neocortical primordia (G). Asterisks in F,G indicate regions also shown at higher magnification (insets). Many cells are double-labeled with ß-gal, indicating their origin in the hem (arrows, and higher magnification insets). A few were positive only for p73 (for example, see arrowhead in G). (H,I) Hem-derived, ß-gal+ cells in the neocortex (H) and hippocampus (I) were reelin-immunoreactive (arrows), although some reelin-positive cells were single-labeled (arrowhead in I). (J,K) Hem-derived cells were not immunoreactive for GABA. cpx, choroid plexus; ncx, neocortex; ob, olfactory bulb; reln, reelin.