The results revealed that Sox5 transcript was detected at very low levels in embryos at early stages up to the gastrula, but was then upregulated and reached peak expression in the
neurula stage, and then was slightly downregulated between tail-bud and hatching.
Patterns of gene expression suggest that initial left-right asymmetry is established at the late gastrula/early
neurula by nodal expression in anterior somites on the left and later in endoderm on the left together with the expression of the nodal antagonist, lefty, on the right (Yu et al., 2002; Onai et al, 2010, 2012).
A twofold destructive/proliferative action of injury itself is fundamental in the organizative phenomena during the late blastula, gastrula and
neurula stages, as shown in the Bufo arenarum species when specimens are submitted to experimental exogenous injury.
Further studies will compare the effects of both all-trans and 9-cis retinoic acid on early
neurula killifish embryos.
Table 1 Schedule for development of Asymmetron lucayanum at 27[degrees]C, with notes on embryonic and larval behavior Stage Time after Figure fertilization 1- and 2-cell 1 h 5A-C 4- and 8-cell 2 h 5D 16- and 32-cell 3 h not shown 64- and 128-cell 4 h not shown Blastula 5 h 5E Mid gastrula 9 h 5F Late gastrula (a) 12 h 5G-I (b) Just-hatched
neurula 15 h 5J-L Early
neurula 19 h 5M, N Mid
neurula (c) 24 h 5O Late
neurula (d) 32 h 5P, Q Hatchet-shaped embryo (d), (c) 50 h 5R-Y Early larva (mouth just open) (f) 3 days 5Z-Z"; 6A-F Feeding larva 5 days 6G-Q (a) Newly produced ectodermal cilia cause embryo to rotate in fertilization envelope.
Electron microscopic study of the development of amphioxus Branchiostoma belcheri tsingtauense: the
neurula and larva.
Six plasmid cDNA libraries were prepared for EST sequencing, two from mixed blastual and gstrula stages, two from mixed late gastrula and
neurula stages, and two from juvfeniles with 2-3 gill slits.
Furthermore, homologs of neural plate border specifiers Msx, Zic, and Pax3/7 are present within the neural plate border territory in late gastrula/early
neurula, suggesting that the initial steps of the border patterning and specification are already present in cephalochordates (Holland et al., 1999; Sharman et al., 1999; Gostling and Shimeld, 2003).
The search identified numerous clones of GFP from unfertilized egg, gastrula,
neurula, larval, and adult libraries for B.
Cell-lineage of the larval nervous system in the ascidian Ciona intestinalis:
neurula stage through to hatched larva.
These genes are initially expressed in the involuting mesoderm of the gastrula, then in the differentiating somites of the
neurula, followed by the differentiating notochord and finally in the tail bud of the 10-somite stage embryo (15).
Retinoic acid modifies the pattern of cell differentiation in the central nervous system of
neurula stage Xenopus embryos.