Fetal and Placental Growth in the Rat following Differential Reduction of Litter Size

Abstract

The effects on fetal and placental growth of differential litter size reduction on day 10 (LR10) and day 13 (LR13) were determined in the rat. LR10 resulted in significant increments in placental weight, fetal body and brain weight, and brain protein content in the survivors at day 21. A marginal effect on brain cellularity (DNA) was observed. Values for these parameters generally followed the extent of reduction. Placenta weight was also related to original litter size. In contrast, LR13 which was associated with survival of supernumerary placentae (those without a fetus) produced no growth enhancement. Prenatal development was discussed in terms of general systemic influences and hormonal regulatory mechanisms.

Litter Size, Maternal Parameters, and Brain and Body Parameters of Neonatal Rats

“…weight, and content of DNA and protein [2,3], These results were also corroborated by others [1,4,5],…”

Selective Ligation of Uterine Artery Branches Accelerates Fetal Growth in the Rat

“…Ligation of one uterine horn in the rat before conception (23), needle aspiration of fetuses in rabbits ( 3 , and crushing (25) or electrocautery (6) of fetuses have all been reported to accelerate the growth of surviving fetuses. The studies reporting these techniques used limited numbers of animals and did not control for the potential effect of litter number on fetal growth.…”

Modeling Trophoblast Cell-Guided Uterine Spiral Artery Transformation in the Rat

“…It is also important to appreciate a disease process such as preeclampsia is inherently problematic to investigate in a polytocous species such as the rat. Litter size and intrauterine position can influence fetal development [ 145 , 146 , 147 , 148 ]. The intrinsic response of a litter-bearing species to an insult that compromises maternal nutrient delivery to the fetus is to sacrifice the health of vulnerable conceptuses allowing the fittest to survive.…”