29.4 Maternal gene products esta blish gradients in early embryogenesis Anterior Posterior Teminal Dorsoventral Matemal somatic torsowke Matemal germline exuperante capwocino trunk gastraston-defeftie identi polehole easter mago nash spatzle Zygotictargets hunchback knops puckebein decapentapfeg Figure 29. 4 Each of the four maternal systems that functions in the egg is initiated outside the egg. The pathway is carried into the egg, where each pathway has a localized product that is the morphogen. This may be a receptor or a regulator of gene expression. The final component is a transcription factor, which acts on zygotic targets that are responsible for the next stage of development 请莘大Figure 29.4 Each of the four maternal systems that functions in the egg is initiated outside the egg. The pathway is carried into the egg, where each pathway has a localized product that is the morphogen. This may be a receptor or a regulator of gene expression. The final component is a transcription factor, which acts on zygotic targets that are responsible for the next stage of development. 29.4 Maternal gene products establish gradients in early embryogenesis