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Fig. 4 | EvoDevo

Fig. 4

From: Analyses of nervous system patterning genes in the tardigrade Hypsibius exemplaris illuminate the evolution of panarthropod brains

Fig. 4

Embryonic He-six3 expression. a–c Fields of He-six3-stained embryos at 24 hpl, 35 hpl, and 45 hpl, respectively. Arrows point to specimens that are enlarged in the inset panels. a–c (Inset) The left inset specimens in panels (a, b) are facing forward, with anterior toward the top. The left inset specimen in panel (c) is facing forward, but rotated slightly left. Solid white lines trace the space between the anterior and posterior ends of the specimens. The right inset specimens in panels (a–c) are laterally mounted, facing right, with anterior toward the top; a dashed line traces the ventral surface. d–f, j–j″ Confocal micrographs. He-six3 expression is shown in green. DAPI labels nuclei (blue). d Dorsal view of a 24 hpl embryo. Dashed lines trace the boundaries between the head and trunk segment 1, and between trunk segments 1 and 2. A dashed line also outlines the developing foregut. The scale bar equals 10 μm. (Inset) A laterally mounted 24 hpl embryo; dashed lines trace segment boundaries. e Frontal view—relative to the head—of a 35 hpl embryo. The solid line traces the ventral surface of the head. Dashed lines outline the inner brain space where neuropil and commissures are located in the fully developed brain. (Inset) The head of the same specimen using the glow LUT in ImageJ to help visualize nuclei. f Oblique view of a 45 hpl embryo. The specimen is laterally mounted, and facing right, but slighted rotated onto its back. Legs on the right side of the body are outlined. g–i DIC images of in situ hybridizations. g, h Laterally mounted embryos. A dashed line traces the ventral surface. i Oblique view of a 45 hpl embryo. The specimen is positioned as in (f), but is a different specimen. A dash line traces the ventral surface of the head and the ventral surface of the posteriormost leg of the right side of the body. j–j″ A laterally mounted 45 hpl embryo. The lateral part of the inner brain space, where neuropil is found in fully developed brains, is outlined. j′–j″ β-tubulin expression is colored red. dnp, dorsal neuropil; fg, foregut; ga1–ga4, ganglion 1–ganglion 4; hpl, hours post-laying; ib, inner brain region; L1–L4, leg 1–leg 4; ob, outer brain region; st, stomodeal complex

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