Figure 5

Genetic ablation of Sema3B in the mouse does not lead to ectopic positioning of spinal motor neurons. (a) As seen in the chick, in the E12.5 mouse trunk, Sema3B is expressed by BC cells located at the spinal cord DREZ (red arrows) and MEP (black arrows). Bar = 100 μm. (b) A quantitative analysis of the incidence of ectopic motor neurons at hindlimb level reveals that there is no significant difference between E12.5 Sema3B null mice and heterozygous and wild-type littermates (n = 3 each). This is in sharp contrast to E12.5 Npn-2 null mice, which is included for comparison (n = 4). **P ≤ 0.01; two-tailed t-test.