Fig. 6. Retinoid signalling promotes the formation of primary neurons in neuralized animal caps. Animal caps were taken from control and experimental embryos injected with either noggin or RAR/RXR mRNA or a combination of these RNAs and grown from the late blastula stage in the presence or absence of 10−7 M RA. The animal caps were assayed at the equivalent of the late neurula stage for the expression of the primary neuron marker, NST. Widespread punctate expression of NST was seen only in animal caps injected with noggin and RAR/RXR mRNA and treated with RA (E). Both non-neuralized animal caps with elevated retinoid signalling (D) and neuralized animal caps with RAR/RXR but no ligand showed no NST expression. The addition of RA to noggin-neuralized animal caps (F) consistently showed a small amount of NST expression clustered to one end of the animal cap (arrowhead). This may reflect the observation that animal caps are heterogeneous and respond to neural induction more strongly on the dorsal side (Sharpe et al., 1987).
Image published in: Sharpe C and Goldstone K (2000)
Copyright © 2000. Image reproduced with permission of the Publisher, Elsevier B. V.
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