Elsevier

Neuroscience

Volume 113, Issue 3, 2 September 2002, Pages 689-698
Neuroscience

Expression patterns of Wnt8b and Wnt7b in the chicken embryonic brain suggest a correlation with forebrain patterning centers and morphogenesis

https://doi.org/10.1016/S0306-4522(02)00171-9Get rights and content

Abstract

The expression patterns of the genes Wnt7b and Wnt8b were analyzed in the brain of chick embryos, having special emphasis in the forebrain. Our results indicated that, at early developmental stages, cWnt8b is expressed in the isthmic organizer and in other areas postulated as forebrain patterning centers, such as the avian cortical hem and the zona limitans intrathalamica (zli). Later in development, cWnt7b becomes expressed in regions neighboring and sometimes overlapping the cWnt8b domains, such as the thalamus on both sides of the zli, or the medial pallium adjacent to the cortical hem. This sequential expression of cWnt8b and cWnt7b is consistent with a role in the patterning and morphogenesis of these forebrain regions.

Section snippets

Experimental procedures

The research conformed the stipulations of the European Community (86/609/EEC) and the Spanish Government (Royal Decree 223/1998) on care and use of laboratory animals. Chicken eggs were incubated in a forced-draft incubator until the desired embryonic stage. The embryos were staged according to Hamburger and Hamilton (1951), and were fixed in 4% paraformaldehyde in phosphate-buffered saline (PBS) at 4°C for 48 h. Early embryos (HH10–30) were processed as whole-mounts, whereas the brains of

cWnt8b

CNS expression of cWnt8b begins before cWnt7b. At HH10–11 (40–48 h of development), cWnt8b is expressed in the presomitic hindbrain, showing a stronger expression in a rostral domain which encompasses the isthmus and rhombomeres 1 and 2 (ist, r1, r2; Fig. 1A). Expression of cWnt8b is also observed in the mesoderm adjacent to the caudal hindbrain, as well as in somites 6–10 in a caudorostral decreasing gradient (Fig. 1A). Light expression is also observed in the secondary prosencephalon (Fig. 1A

Discussion

The Wnt family of genes encode cysteine-rich proteins suggested to act as morphogens and to participate in tissue patterning and morphogenesis (Roelink and Nusse, 1991, Parr and McMahon, 1994, Cadigan and Nusse, 1997). The present results indicate that both the avian cxh and zli express Wnt8b in the chick embryo, which may play a role in the morphogenesis of the flanking territories, such as the choroid plexus, the medial pallium, and parts of the diencephalon. Interestingly, the cxh and the

Acknowledgements

This work was supported by the Seneca Foundation (PB/14/FS/97 to L.P. and PB/25/FS/99 to L.M.), and the Spanish Ministry of Science and Technology (DGI grants PB98-0397 to L.P., BFI2000-1359-C02-02 to L.M., and 1FD1997-2090 to A.L.G.).

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