Table 1. Results of congenic breeding by round spermatid injection (ROSI) in three gene-modified strains.
| Strain | Generation produced | Age (day) of male used for ROSI | No. of oocyes that survived ROSI | No. (%) of oocytes that developed to 2-cells | No. of 2-cells transferred | No. (%) implanted | No. (%) born | No. (%) of males born | No. (%) of male carriers |
| Vasa-Venus transgenic | N1 | Adult (ICSI) | 16 | 15 (93.8 ) | 15 | 10 (66.7 ) | 5 (33.3 ) | 5 (33.3 ) | 5 (33.3)* |
| N2 | 24 | 182 | 164 (90.1 ) | 164 | 69 (42.1 ) | 24 (14.6 ) | 12 (7.3 ) | 4 (2.4 ) | |
| N3 | 23 | 123 | 109 (88.6 ) | 109 | 24 (22.0 ) | 4 (3.7 ) | 2 (1.8 ) | 1 (0.9 ) | |
| N4 | 22 | 172 | 156 (90.7 ) | 156 | 51 (32.7 ) | 14 (9.0 ) | 6 (3.8 ) | 2 (1.3 ) | |
| N5 | 23 | 134 | 123 (91.8 ) | 123 | 23 (18.7 ) | 10 (8.1 ) | 4 (3.3 ) | 2 (1.6 ) | |
| Ednra-EGFP knockin** | N1 | Adult (IVF) | 166 | 135 (81.3 ) | 135 | 62 (45.9 ) | 49 (36.3 ) | 23 (17.0 ) | 12 (8.9 ) |
| N2 | 24 | 243 | 196 (80.7 ) | 196 | 63 (32.1 ) | 30 (15.3 ) | 10 (5.1 ) | 5 (2.6 ) | |
| N3 | 24 | 261 | 235 (90.0 ) | 235 | 107 (45.5 ) | 52 (22.1 ) | 30 (12.8 ) | 14 (6.0 ) | |
| N4 | 25 | 244 | 215 (88.1 ) | 215 | 72 (33.5 ) | 39 (18.1 ) | 19 (8.8 ) | 11 (5.1 ) | |
| ENU-induced mutant | N1 | Adult (IVF) | 80 | 49 (61.3 ) | 49 | Not observed | 26 (53.1 ) | 14 (28.6 ) | 3 (6.1 ) |
| N2 | 25 | 201 | 158 (78.6 ) | 158 | 54 (34.2 ) | 25 (15.8 ) | 11 (7.0 ) | 4 (2.5 ) | |
| N3 | 23 | 208 | 194 (93.3 ) | 194 | 68 (35.1 ) | 26 (13.4 ) | 12 (6.2 ) | 7 (3.6 ) | |
| N4 | 22 | 173 | 127 (73.4 ) | 127 | 51 (40.2 ) | 13 (10.2 ) | 5 (3.9 ) | 2 (1.6 ) | |
| N5 | 24 | 216 | 177 (81.9 ) | 177 | 91 (51.4 ) | 34 (19.2 ) | 10 (5.6 ) | 4 (2.3 ) | |
| Total (ROSI only) | 2157 | 1854 (86.0 ) | 1854 | 673 (36.3 ) | 271 (14.6 ) | 121 (6.5 ) | 56 (3.0 ) | ||
| Control (C57BL/6) | 22–24 | 467 | 349 (74.7 ) | 329 | 133 (40.4 ) | 49 (14.9 ) | 26 (7.9 ) | ||
*
The implantation sites were identified as the scars of decidualization at caesarian section.
**
The donor male (N0) was homozygous for the transgene.
***
All genetic markers tested were homozygous for the B6 mouse strain at N3.