Fig. 2. Widespread sympathetic neuron loss without migration defects in postnatal Egr3-deficient mice. (A) Sympathetic neuron loss was detected in the SCG from Egr3^-/- mice starting 1 day after birth (P1). Approximately 30% of SCG neurons were lost between P0 and P1, and the difference between wild-type and Egr3^-/- mice persisted in aged adult mice when the overall numbers declined because of physiological attrition of senescent neurons (results from three or four SCG per genotype and developmental time point; ^*P<0.05, Student's t-test relative to wild type). (B-E) At P1, the sympathetic ganglia were properly positioned along the rostral-caudal axis. (B) The SCG was smaller (black arrowhead) and many axon bundles emanating from it were either absent (broken outline) or markedly atrophic (white arrowhead) in Egr3^-/- mice. Similarly, (C) the stellate ganglion (STG; black arrowhead), (D) the thoracic paravertebral chain ganglia and (E) caudal sympathetic ganglia were consistently smaller (black arrowheads), and there was atrophy and loss of projections emanating from them (white arrowheads) (representative results from three P1 Egr3^+/+:DlZ and Egr3^-/-:DlZ mice; scale bars: 250 µm).