Table 2. Toxic effects of hyaluronidase, ALT-BC4, and ICSI Cumulase^® on embryonic development

Group1)	No. of oocytes	Rate of embryo development (%)
		2-cell	4-cell	8-cell	16-cell	Morula	Blastocyst
V2)	152	97.8 ± 1.2	88.1 ± 1.7	65.2 ± 3.6	51.4 ± 2.0	45.6 ± 4.0	44.7 ± 4.7
2S3)	158	92.6 ± 0.4	86.1 ± 3.7	66.2 ± 2.0	48.3 ± 4.4	41.6 ± 4.3	40.7 ± 3.5
2A	155	99.2 ± 0.8*	96.1 ± 2.1*	77.5 ± 4.0	63.4 ± 3.8	63.4 ± 3.8*	63.4 ± 3.8*
20A	158	94.1 ± 2.4	86.4 ± 2.8	67.5 ± 5.0	44.7 ± 7.2	40.7 ± 6.7	39.8 ± 5.8
2C	152	93.6 ± 3.7	87.0 ± 3.6	72.7 ± 9.5	56.4 ± 9.2	46.5 ± 7.1	46.5 ± 7.1
20C	157	96.6 ± 1.7	94.1 ± 1.8	84.5 ± 2.3*	52.0 ± 2.3	47.2 ± 3.7	43.7 ± 2.7

The COCs were exposed to 800 U/mL hyaluronidase for 2 min (2S); 80 U/mL ALT-BC4 for 2 (2A) and 20 min (20A); and 80 U/mL ICSI Cumulase^® for 2 (2C) and 20 min (20C). Results are expressed as the mean ± SEM (n = 3).
Negative control (V), the cumulus-oocyte complexes (the COCs) were pipetted in the NCSU-23 washing medium for denuding.
Positive control (2S), the traditional denuding method that removed cumulus cells from the oocytes using 800 U/mL hyaluronidase for 2 min.
Values differ significantly compared with the positive control (2S) (p < 0.05).