Embryos injected with emx3 morpholino antisense oligonucleotides (MO) form abnormal axon tracts, lack olfactory glomeruli, and have normal cell division patterns. A-D: Acetylated tubulin labeling of axons; 35 hr; emx3 knockdown embryos lack anterior commissure (AC in B,D). The supraoptic tract (SOT) is present but not fasciculated (arrows in A,B). Similarly, the olfactory nerve (on) that extends from the developing olfactory organ (o) to the dorsal telencephalon (t) is defasciculated in emx3 knockdown embryos (arrows in C,D). E,F: emx3MO injected embryos have fewer presumptive olfactory glomeruli (yellow asterisks), visualized by Bodipy-ceramide staining. As in (G,H), the characteristic morphology of the ventricular zone appears broader in emx3MO embryos. G,H: Five minutes of 5-bromo-2-deoxyuridine (BrdU, white) incubation labels cells in S-phase. In control- and emx3MO-injected embryos at 24 hr, BrdU labeled cells are located in a 3-4 cell-wide region close to the ventricular zone. Mitotic cells, labeled by anti-phosphorylated histone H3 (pH3, green), are located on the ventricular side of the telencephalon in both tp53MO and emx3MO injected embryos. I-K: The number (K) and dorsoventral distribution (I-K) of pH3 positive cells in the medial telencephalic ventricular zone is the same in control (I,K) and emx3MO injected embryos (J,K). I,J: Projections of the side view confocal stack used for cell counts in K; the dotted line indicates the border between dorsal and ventral telencephalon, error bars denote SEM. Anterior is to the left, dorsal to the top. Confocal projections of oblique (A,B) straight (C-H) frontal views, dorsal to the top. os, optic stalk; POC, postoptic commissure. Scale bars = 50 μm.
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