Practice question

Syncytial specification occurs before cellularization, particularly in Drosophila where nuclear divisions proceed without cytokinesis, producing a multinucleate syncytium sharing common cytoplasm. Maternal morphogen gradients such as Bicoid anterior and Nanos posterior diffuse freely among nuclei without membrane barriers, directly entering nuclei and establishing concentration-dependent transcriptional zones by binding enhancers of gap genes with different affinities. Nuclei interpret gradients autonomously, yet pattern emerges without cell contact. After cellularization, cells retain programmed identities. This mechanism allows rapid, long-range patterning unimpeded by plasma membranes during early development.