Miyamoto H, Manabe N, Mitani Y, Sugimoto N, Watanabe T, Aruga C, Sato E
Department of Animal Science, Kyoto University, Japan.
J Exp Zool. 1995 Jun 1;272(2):116-22. doi: 10.1002/jez.1402720205.
Female reproductive properties, early embryonic development, and serum estradiol and progesterone levels of the senescence-accelerated mouse (SAM)-prone (SAM-P) strain were compared with those of a SAM-resistant (SAM-R) strain. The reproductive life span of SAM-P (from 11.4 to 25.0 weeks old) was shorter than that of SAM-R (11.1 to 41.6 weeks old), and the total number of SAM-P pups was 41.7% less than from SAM-R. The reproductive senescence of SAM-P is more accelerated than that of SAM-R. At 15 weeks old, the maximum litter size of SAM-P was noted and was 33.7% smaller than that of SAM-R. Although no differences in the numbers of ovulated and fertilized ova were observed between two strains, the number of implants in SAM-P was 21.6% less than in SAM-R. Cell cleavage was delayed in embryos of SAM-P (8% morula, at day 2 of pregnancy) compared to SAM-R (48%). At day 3 of pregnancy, 9% and 33% of the embryos were blastocysts in SAM-P and SAM-R, respectively. At day 1 of pregnancy, serum estradiol level in SAM-P was 18.2% higher than in SAM-R, whereas the serum progesterone level in SAM-P was 46.2% lower than in SAM-R. The unbalance of estradiol and progesterone levels in SAM-P was considered to be the cause of the delay in early embryonic development, and then the decrease of implantation and a smaller litter size.
将易衰老小鼠（SAM）-易感性（SAM-P）品系的雌性生殖特性、早期胚胎发育以及血清雌二醇和孕酮水平与SAM抗性（SAM-R）品系进行了比较。SAM-P的生殖寿命（11.4至25.0周龄）短于SAM-R（11.1至41.6周龄），且SAM-P幼崽的总数比SAM-R少41.7%。SAM-P的生殖衰老比SAM-R加速得更快。在15周龄时，观察到SAM-P的最大窝仔数，比SAM-R小33.7%。尽管两个品系之间排卵和受精卵的数量没有差异，但SAM-P的着床数比SAM-R少21.6%。与SAM-R（48%）相比，SAM-P胚胎的细胞分裂延迟（妊娠第2天桑椹胚占8%）。在妊娠第3天，SAM-P和SAM-R的胚胎分别有9%和33%为囊胚。在妊娠第1天，SAM-P的血清雌二醇水平比SAM-R高18.2%，而SAM-P的血清孕酮水平比SAM-R低46.2%。SAM-P中雌二醇和孕酮水平的失衡被认为是早期胚胎发育延迟的原因，进而导致着床减少和窝仔数变小。
