Schlapp Geraldine, Meikle Maria Noel, Silva Cecilia, Fernandez-Graña Gabriel, Menchaca Alejo, Crispo Martina
Transgenic and Experimental Animal Unit, Institut Pasteur de Montevideo, Montevideo, Uruguay.
Servicio Médico Integral, Montevideo, Uruguay.
Anim Reprod. 2020 Nov 24;17(4):e20200524. doi: 10.1590/1984-3143-AR2020-0524.
The objective was to evaluate the influence of colony aging in a Swiss Webster (SW) outbred stock used as recipients for embryo transfer. In the first study, a retrospective analysis was performed throughout several generations during a 38-month period in 2,398 embryos transferred to 108 SW recipients. A decrease in the percentage of live pups from transferred embryos was found at the end of the period. Impairment occurred due to the incidence of maternal cannibalism that increased from 0% to 67-100% (P<0.05), while pregnancy rate (pregnant/transferred recipients) and number of pups per delivered female were not affected throughout the period (P=NS). A following study was carried out to compare the reproductive performance of SW stock vs. B6D2F1 hybrid females in a 5-year interval. The study was conducted on a total of 893 embryos transferred to 40 females (20 SW and 20 B6D2F1) in Year #1, and 514 embryos transferred to 30 females (15 SW and 15 B6D2F1) in Year #5. No cases of maternal cannibalism were found on Year #1 in any of the strains (0/10 and 0/10). However, an incidence of 44,4% (4/9) was seen on Year #5 for SW, while for B6D2F1 the incidence was 0% (0/12) (P<0.05). Further examination of the uterus showed endometrial cysts and abnormal implantation sites in SW on Year #5 but not in B6D2F1 females. In conclusion, this study reports an impairment of the reproductive performance of an early aged SW outbred stock colony mainly due to the occurrence of maternal cannibalism. This finding has important implications for embryo transfer programs conducted in mouse facilities.
目的是评估作为胚胎移植受体的瑞士韦伯斯特（SW）远交群小鼠群体老化的影响。在第一项研究中，对38个月期间几代的情况进行了回顾性分析，共向108只SW受体移植了2398枚胚胎。在该时期结束时，发现移植胚胎所产活仔百分比下降。这种损害是由于母鼠食仔发生率从0%增加到67%-100%（P<0.05），而整个时期妊娠率（妊娠受体/移植受体）和每只分娩母鼠所产仔数未受影响（P=无显著性差异）。随后进行了一项研究，比较SW群体与B6D2F1杂交雌性小鼠在5年期间的繁殖性能。该研究在第1年共向40只雌性小鼠（20只SW和20只B6D2F1）移植了893枚胚胎，在第5年向30只雌性小鼠（15只SW和15只B6D2F1）移植了514枚胚胎。在第1年，任何一个品系均未发现母鼠食仔情况（0/10和0/10）。然而，在第5年，SW的发生率为44.4%（4/9），而B6D2F1的发生率为0%（0/12）（P<0.05）。对子宫的进一步检查显示，在第5年SW出现了子宫内膜囊肿和异常着床部位，而B6D2F1雌性小鼠未出现。总之，本研究报告了早期老化的SW远交群小鼠群体繁殖性能受损，主要原因是母鼠食仔现象的发生。这一发现对小鼠设施中进行的胚胎移植项目具有重要意义。
