ISSN:
0002-9106
Keywords:
Life and Medical Sciences
;
Cell & Developmental Biology
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Medicine
Notes:
This study was conducted to determine if there is a greater variation in fetal weight and/or placental weight among litters of rat fetuses than within a single litter. Three hundred and twenty-seven litters comprising 1,979 fetal and placental weights were analyzed using analysis of variance within versus among litters. There was a definite litter effect, i.e., variation in fetal and placental weight was greater (p 〈 0.05) among litters than within litters. The variation in fetal and placental weights between litters became greater with increasing litter size. Experimentally limiting the litter size early in gestation does not reduce or eliminate the litter effect. This litter effect means that individual fetuses from several rat pregnancies cannot be considered to have come from a common universe and, therefore, the number of litters and their mean growth data are much more meaningful than the number of embryos in an experiment. When designing research programs in which embryonic and placental growth in rats are to be evaluated, it is more important to establish the experimental goal on the basis of the total number of litters rather than the total number of embryos per experimental or control group.
Additional Material:
1 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/aja.1001280205
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