The expression pattern is almost identical to that of endogenous tll.
Expression of tll as detected by a lacZ reporter encompasses a broad area of the prospective protocerebrum in the procephalic neurectoderm. Expression in procephalic neuroblasts stage 9-11: deuterocerebrum - d2, d3, d6, d8, d10, d13, v1-3; protocerebrum - ad1-18, av1, cd1-21, cv1-9, pd1-20, pv1-3 (all)
Expression in syncytial and cellular blastoderms is observed to be nearly identical to that of endogenous toll.