Extended Data Figure 2: Adult and embryonic brains of E. burgeri, and gene expression and nervous system staining of stage-45 embryo.
From: Evidence from cyclostomes for complex regionalization of the ancestral vertebrate brain
a, b, Dorsal view (a) and sagittal section (b) of the adult brain of E. burgeri. c–h, E. burgeri embryos at Bashford Dean stages 45 (c–e) and 53 (f–h)17,18. Dorsal (c, f) and lateral (d, g) views are shown. e, h, Sagittal sections stained with haematoxylin and eosin. Dean stage 53 is very similar to the embryo described in figure 1 in ref. 45. i–t, A stage 45 E. burgeri embryo observed using histological preparations. Dotted lines indicate the presumptive telencephalic border estimated by EmxB and FoxG expressions21,22. At this stage, Nkx2.1/2.4 and Hh2 have not been expressed yet in the rostral telencephalon (according to the prosomeric model3). cer, cerebrum; met, metencephalon; mes, mesencephalon; ob, olfactory bulb. See Figs 1, 2 and 4 for other abbreviations. Scale bars, 2.0 mm (a–c and f), 1.0 mm (e, h) and 500 μm (i, j).