RELN and hydrops fetalis: The main findings in this study are that (i) expression of reelin in the SGZ is higher in the dorsal than the ventral DG, (ii) nicotine exposure had no significant effect on reelin expression in the hippocampus and DG, (iii) IHH exposure decreased reelin expression in the SP and HF layers of CA1, and with (iv) no additional impact on reelin expression due to duration of IHH exposure.