Figure 1.

Expression of DCX⁺ Clusters in the Dentate Gyrus during Mouse Development

(A) Doublecortin (DCX) is expressed by immature neurons in the dentate gyrus (DG) after birth. No DCX⁺ clusters were readily visible in either wild-type (WT) or BACE1-null mice at early developmental stages (postnatal day 3 [P3] and P6). At P8, scatted DCX⁺ cells were detected in the transient subpial zone (SPZ)/marginal zone (MZ) in WT mice as well as small DCX⁺ clusters in the SPZ/MZ in BACE1-null mice (arrow). From P10 to P20, more DCX⁺ clusters were formed in the SPZ/MZ and were even observed in the molecular layer (ML) of BACE1-null DG, which are very rarely detected in WT P10 mice. The expression of DCX gradually decreased in DG during development. DCX⁺ clusters were found in close proximity to the granule cell layer (GCL) (arrowhead) at P30. Nuclei were labeled with TOPRO. Scale bars, 100 μm.

(B) Areas occupied by clustered cells were quantified by ImageJ and divided by the total DG area in the field. The percentage of clustered cell area was plotted from mice at the ages of P8, P20, and P30 (n = 5 pairs; ^∗∗∗p < 0.01, Student's t test).