Temporal and spatial delineation of mouse Otx2 functions by conditional self-knockout.

To identify the independent spatial and temporal activities of the essential developmental gene the Otx2, the germline mutation of which is lethal at embryonic day 8.5, we floxed one allele and substituted the other with an inducible CreER recombinase gene. This makes 'trans' self-knockout possible at any developmental stage. The transient action of tamoxifen pulses allows time-course mutation. We demonstrate efficient temporal knockout and demarcate spatio-temporal windows in which Otx2 controls the head, brain structures and body development.