Fig. 5. Birthdating analysis of neurons in the striatum. (A) BrdU was administered at different embryonic time-points (E10.5-E15.5), and the striatum was subsequently analyzed at E18.5. BrdU-positive neurons were counted with respect to their localization within the striatal compartments (SCS, patch or matrix). The SCS neurons born at E12.5 are significantly increased in Foxg1Cre; N1 cKOs, whereas neurons born at E12.5 in the patch compartment are significantly decreased in mutants compared when with wild-type littermates. Equivalent numbers of matrix neurons are born in the mutants and in wild-type littermates, except at E11.5, at which time there is a small but statistically significant decrease in the birth of matrix neurons in Foxg1Cre; N1 cKOs. A single asterisk (^*) denotes a P-value of <0.05, whereas two asterisks (^**) signify a P-value of <0.005. Three Foxg1Cre; N1 cKOs and three wild-type embryos were analyzed for each time-point. Error bars represent s.e.m. (B) Coronal sections of the striatum at E18.5 with three representative ages of BrdU administration in Foxg1Cre; N1 cKOs and wild-type littermates. Tissue was immunostained with antibodies to Darpp32 (red) to visualize the SCS and patch compartments, and with antibodies to BrdU (green) to detect cells that become postmitotic shortly after the pulse of BrdU. Scale bar: 250 µm.