Table 2.

Time-course changes in the hedgehog frequency in the corneal epithelial cells of rabbit

Compounds	Frequency of hedgehog (%)
	0.5 h	2 h	4 h	6 h	24 h
Saline	0.2 ± 0.6	1.1 ± 1.2	0.7 ± 1.0	0.7 ± 0.0	0.4 ± 0.6
1% EtBr	3.6 ± 2.5	3.3 ± 1.7	8.9 ± 3.5a	1.6 ± 2.3	0.4 ± 0.6
3% MMS	12.9 ± 7.8a	13.6 ± 8.3a	10.7 ± 1.0a	8.0 ± 2.0a	2.0 ± 1.0a
1% 4-NQO	9.8 ± 8.5a	3.8 ± 2.9	1.3 ± 1.0	1.1 ± 0.6	2.0 ± 2.0a

Data are presented as the mean ± SD (n = 3)

EtBr Ethidium bromide, MMS Methyl methanesulfonate, 4-NQO 4-nitroquinoline 1-oxide

^aSignificantly higher than the negative control group at 5% probability level (Student’s t-test, one-tailed)