Practice question

Lateral inhibition describes feedback where cell adopting primary fate inhibits neighbors through contact-mediated signal preventing same fate adoption. In Drosophila neuroectoderm, prospective neuroblast expresses high Delta activating Notch in surrounding cells. Notch induces Enhancer of split complex repressing proneural genes achaete-scute, forcing neighbors toward epidermal fate and limiting neuroblast density. This generates spaced array of neuroblasts separated by epidermis. BMP gradient in limb bud specifies digit identity via thresholds, not inhibitory cell-cell choice. Notch-Delta neuroblast singling out is textbook lateral inhibition model also seen in inner ear patterning.