Xenbase Image ID: 145529

Fig. 1. Cortical rotation and the segregation of maternal gene products in the cleavage stage embryo. A. Orientation of early cell divisions. The first cleavage plane is determined by the sperm entry point (SEP) and the animal–vegetal (A–V) axis. The second cleavage is orthogonal to the first but still contains the A–V axis; dorsal blastomeres are defined in the hemisphere opposite the SEP. The third cleavage is slightly above the equator. B. Displacement of maternal gene products. The egg contains vegetally localized maternal gene products. A microtubule network is set up at fertilization and the outer layer, or cortex, of the single cell embryo rotates to displace the vegetal cortical region away the SEP. Maternal gene products are displaced by movement with the cortex or by vesicle trafficking into the presumptive dorsal hemisphere, and are further segregated by subsequent cell divisions. Image published in: De Domenico E et al. (2015) © 2015 The Authors. This image is reproduced with permission of the journal and the copyright holder. This is an open-access article distributed under the terms of the Creative Commons Attribution license Larger Image Printer Friendly View

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