Table 2.

Parameters and results of stereological analysis of hippocampal neuron numbers in control and chronic DA sea lions known or suspected of previous exposure to domoic acid.

	Granule cell layer	Hilus	CA3	CA2	CA1
Counting grid	200 × 200 µm	200 × 200 µm	400 × 400 µm	200 × 200 µm	500 × 500 µm
Counting frame	20 × 20 µm	50 × 50 µm	50 × 50 µm	50 × 50 µm	50 × 50 µm
Cells counted / hippocampus (mean ± s.e.m.)	260 ± 16	207 ± 16	231 ± 15	227 ± 15	283 ± 14
Coefficient of variation	0.44	0.56	0.48	0.36	0.49
Mean coefficient of error*	0.06	0.10	0.08	0.10	0.06
Neurons / hippocampus of control sea lions (n=9 animals, 18 hippocampi) (mean ± sem)	2,120,000 ± 350,000	333,000 ± 14,000	1,350,000 ± 170,000	332,000 ± 98,000	2,310,000 ± 300,000
Neurons / hippocampus of chronic DA sea lions (n=14 animals, 17 affected hippocampi) (mean ± sem)	1,150,000 ± 250,000**	68,100 ± 9,400***	433,000 ± 51,000***	117,000 ± 14,000***	1,260,000 ± 120,000***
Neurons / hippocampus of chronic DA sea lions (n=11 animals, 11 unaffected hippocampi) (mean ± sem)	2,470,000 ± 140,000	349,000 ± 12,000	1,570,000 ± 60,000	386,000 ± 27,000	2,670,000 ± 110,000

^*Calculated according to West et al. (1991).

^***Significantly different from controls and unaffected hippocampi in chronic DA sea lions or

^**only different from unaffected hippocampi, p<0.05, ANOVA on ranks with Dunn’s method.