SPACING OF FETUSES AND LOCAL COMPETITION IN STRAINS OF MICE WITH LARGE, MEDIUM AND SMALL LITTERS
SPACING OF FETUSES AND LOCAL COMPETITION IN STRAINS OF MICE WITH LARGE, MEDIUM AND SMALL LITTERS
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DOI：
10.1530/jrf.0.0950783
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发表时间：
1992-08-01
期刊：
影响因子：
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通讯作者：
WELLSTEAD, JR
中科院分区：
文献类型：
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作者：
BRUCE, NW;WELLSTEAD, JR
在三个品系的小鼠身上，研究了胎儿沿着子宫角均匀分布的趋势及其与胎儿之间局部竞争的关系，这三个品系的小鼠分别产下了大、中、小窝。通过将每个子宫角内每个胎儿或胎盘的重量与到其近邻的平均距离相关联来评估局部竞争。分别在妊娠第19天、分娩前一天和第7天测量体重和距离，平均活胎数(平均活胎数)大、中、小窝分别为16.3+/-0.9、11.7+/-0.6和7.2+/-0.5(n=7、7和10)。在第19天，大品系(10.1+/-1.0 mm)的平均胎距显著小于中等品系(14.0+/-1.2 mm)和小品系(13.5+/-1.0 mm)。从妊娠第7天到第19天，所有三个品系的胎龄均匀度(用胎间距离除以平均距离的标准差)都有所改善，并有效地防止了中窝(r=0.04)和小窝(r=0.17)之间的局部竞争，但在大窝(r=0.45，P<；0.01)。因此，局部拥挤似乎不会对小鼠的胎儿生长有害，除非是专门为大窝小鼠培育的品系。
The tendency for fetuses to be evenly spaced along the uterine horn and the relationship of this to local competition between fetuses was examined in three strains of mice which characteristically produce large, medium and small litters. Local competition was assessed by correlating, within each uterine horn, the weight of each fetus or placenta with the mean distance to its immediate neighbours. Weights and distances were measured on day 19 of gestation, on the day before expected parturition and distances only on day 7.Average litter sizes (live fetuses) were 16.3 +/- 0.9, 11.7 +/- 0.6 and 7.2 +/- 0.5 (mean +/- SEM) in the large, medium and small litter strains, respectively (n = 7, 7 and 10, respectively). On day 19, the mean distance between fetuses was significantly less (P < 0.05) in the large strain (10.1 +/- 1.0 mm) than in the medium (14.0 +/- 1.2 mm) or small (13.5 +/- 1.0 mm) strains. Evenness of spacing, expressed as the standard deviation of distances between fetuses divided by the mean distance, improved from day 7 to day 19 of gestation in all three strains and effectively prevented local competition between fetuses in the medium litter (r = 0.04) and small litter strains (r = 0.17), but not in the large litter strain (r = 0.45, P < 0.01). Thus, local crowding does not seem to be detrimental to fetal growth in mice, except in strains specifically bred for large litters.