NTN mRNA appears sequentially in the ventral midbrain (vm) and caudate putamen (cp) of the developing mouse brain. Sections of E13.5 brain hybridized with antisense probe to NTN (A) display strong hybridization in the ventral midbrain (vm), whereas no hybridization is seen in the developing caudate putamen (cp) above the background seen with sense strand control probe (B). At P1, (C, E, G) as well as in the adult brain (D, F) hybridization is seen in both the ventral midbrain and caudate putamen. The signal in the adult caudate (F, H) is associated with cells displaying a nuclear morphology characteristic of neurons. Scale bars:B, E, F, 1 μm (these apply to A, C,D, respectively); G, 1 μm;H, 0.1 μm.