Pregnant cd 1 dams

The vertebrate animal experimental protocols were approved by the Harvard University Institutional Animal Care and Use Committee and were performed in accordance with institutional and federal guidelines. For in utero electroporation experiments, we ordered timed pregnant CD-1 dams from Charles River Laboratories, and performed in utero electroporation of fluorescent labeling constructs at E14.5 or E15.5. For SCPN retrograde labeling experiments, we ordered pregnant CD-1 dams from Charles River Laboratories, and performed ultrasound-guided injections into the cerebral peduncles of the P1 litter. We report developmental stages for all experiments in the descriptions of the experiments. All experiments except the individual cortical hemisphere experiments used mixed groups of male and female animals, and in the individual cortical hemisphere experiment we did not record the sex of each individual animal due to the difficulty of both rapidly and accurately determining sex at this developmental stage. We acknowledge that our results are limited in that they do not allow analysis of sex-specific effects.