Table 1.

Neuronal cell density in the motor cortex of FGF2 null mice

Layer	Number of cells/area unit		Δ, %	Significance
	FGF2+/+	FGF2−/−
I	5.42  ±  1.38, n = 20 (103)	5.68  ±  1.70, n = 20 (108)		P > 0.1
II	30.70  ±  5.51, n = 20 (614)	24.78  ±  6.37, n = 20 (471)	20	0.001 < P < 0.005
III	15.98  ±  4.26, n = 60 (991)	14.43  ±  3.73, n = 56 (823)	10	0.01 < P < 0.05
IV	17.50  ±  4.50, n = 64 (1103)	15.54  ±  4.37, n = 64 (979)	12	0.005 < P < 0.01
V	15.97  ±  2.90, n = 44 (719)	10.55  ±  2.18, n = 36 (388)	34	P < 0.0005
VI	18.27  ±  3.80, n = 64 (1151)	14.41  ±  4.15, n = 64 (894)	22	P < 0.0005

Data show cresyl violet-positive cells per area unit of layers I–VI of the motor cortex of FGF2^−/− compared with FGF2^+/+ mice. Mean values ± SD are shown. n, total number of areas counted. The total numbers of cells counted are shown in parenthesis. Stained cells were counted with a Zeiss Axioplan-2 microscope by using a 10 × 10 micrometer grid and a ×40 objective. Three different depths of field were counted, and each count included only cells that were in sharp focus. Counts were obtained from four sets of matching sections, corresponding to four FGF2^+/+ and four FGF2^−/− animals, respectively. Each animal was equally represented in the counting. Δ, decrease in cell density in the FGF^−/− sections. The data were analyzed statistically by using a two-sample (pooled) t test.