Table 4.

Postimplantation development of oocytes fertilized by ICSI with fresh, frozen, or freeze-dried spermatozoa

Sperm treatment	Medium for sperm dispersion and storage	Mouse strain	Sperm storage time, days	No. 2-cell embryos* transferred (No. exps.)	No. recipients†	Examination on day 14 post coitum
						No. (%) implants	No. (%) normal fetuses	Range
Fresh	Hepes-CZB	B6D2F1	—	94 (8)	12	75 (80)	54 (57)b	0–83
		C57BL/6J	—	48 (6)	6	36 (75)	26 (54)c	29–73
		129/SvJ	—	54 (4)	4	37 (69)	22 (41)	13–58
		BALB/c	—	65 (4)	4	36 (55)	16 (25)	14–40
Frozen and kept at −75°C	EGTA‡	B6D2F1	Up to 28	66 (4)	8	46 (70)	31 (47)	14–70
		C57BL/6J	Up to 28	76 (7)	8	68 (89)a	42 (54)d	30–90
		129/SvJ	Up to 42	43 (4)	4	31 (72)	19 (44)	38–67
Freeze-dried and kept at 4°C	EGTA‡	B6D2F1	Up to 14	98 (5)	8	72 (73)	37 (38)b	11–56
		C57BL/6J	Up to 56	176 (17)	18	112 (64)a	43 (24)c,d	0–69
		129/SvJ	Up to 56	60 (6)	6	46 (77)	24 (40)	27–50
		BALB/c	Up to 35	75 (6)	6	58 (77)	16 (21)	6–40

Statistically significant χ² comparisons between treatments within strains:  

^a,  

^c, and  

^d, P < 0.001;  

^b, P < 0.01. 

^*In all strains two-cell embryos were derived from syngeneic gametes. 

^† CD-1 females (albino) mated with vasectomized CD-1 males (albino). Two-cell embryos transferred on the first day of pseudopregnancy. 

^‡ Composition of EGTA medium: 50 mM NaCl, 50 mM EGTA, and 10 mM Tris⋅HCl.