Table 1.

Number and percentage of L1ir orphan and synaptic boutons in the stratum radiatum of NP−/− and NP+/+ mice

Proximal Middle Distal
Number % Number % Number % n
Orphan boutons
NP+/+ L1ir 70.5±11.5 (83.4±5.2) 62.6±10.6 (64.6±4.6) 83.8±10.8 (71.2±3.3) 8
L1ir-neg 11.5±3.1 (16.6±5.2) 31.3±5.0 (35.4±4.6) 32.5±4.7 (28.8±3.3) 8
Total 82.1±10.7 93.9±11.3 116.3±12.2 8
NP−/− L1ir 142.6±28.8* (83.7±3.4) 134.2±28.9* (74.4±4.6)* 145.9±24.3* (83.9±2.5)** 8
L1ir-neg 19.2±2.0 (16.3±3.4) 28.9±3.8 (25.6±4.6)* 24.0±2.6 (16.1±2.5)** 8
Total 161.8±28.8* 163.0±35.8* 169.9±24.9 8
Synaptic boutons
NP+/+ L1ir 9.0±2.1 (3.8±0.9) 11.3±2.0 (4.9±0.8) 13.7±1.9 (6.1±0.9) 7
L1ir-neg 223.1±3.8 (96.2±0.9) 219.7±8.4 (95.1±0.8) 214.6±11.4 (93.9±0.9) 7
Total 232.1±4.3 231.1±8.8 228.3±11.6 7
NP−/− L1ir 16.4±2.7* (8.1±1.2)** 21.0±2.6* (10.4±1.8)** 18.2±4.5 (9.2±2.7) 7
L1ir-neg 188.4±12.2** (91.9±1.2)** 191.9±17.7 (89.6±1.8)** 191.0±18.3 (90.8±2.7) 7
Total 204.8±12.8* 212.9±17.0 209.1±17.5 7
  • The numbers of boutons per 1000 μm2 in proximal, middle and distal regions from the CA1 soma were counted (mean ± s.e.m.) and the percentages of L1ir and L1ir-negative (L1ir-neg) synaptic and orphan boutons per total (L1ir and L1ir-neg) are shown. Significant changes in the number and percentage of L1ir synaptic and orphan boutons between NP−/− and NP+/+ mice (Student's unpaired t-test) are indicated. *P<0.05; **P<0.01.