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Differences in placental structure during gestation associated with large and small pig fetuses.
J Anim Sci. 2007 Dec; 85(12):3267-75.JA

Abstract

The efficiency of nutrient transport from the pregnant female pig to the developing fetus depends on the size and function of the placenta. It has been reported that maternal and fetal blood vessels are arranged in a cross-countercurrent arrangement within placental microscopic folds. Thus, the blood supplies are in close apposition to each other within these microscopic folds, and maternal and fetal blood flows in approximately opposite directions perpendicular to the plane of the placenta. This arrangement indicates that the width of the microscopic folds influences placental efficiency. The objective of this study was to determine whether differences in pig placental microscopic fold development are associated with differences in fetal size or are influenced by selection for ovulation rate or uterine capacity. Gilts from a randomly selected control line, a line selected for ovulation rate, and a line selected for uterine capacity were slaughtered, and uterine wall samples were collected within the placentas associated with the largest and smallest fetuses in each litter on d 45, 65, 85, and 105 of gestation. The uterine wall samples were processed for histology and analyzed using computer-assisted morphometry. Average width of the placental folds and average width of the placental stroma above the folds were measured. To measure fold complexity, the length of the epithelial bilayer for a given length of placenta was also measured. The width of the folded bilayer increased significantly from d 65 to 105 and was greater in placentas associated with small fetuses compared with large fetuses on d 105 of gestation. In contrast, the width of the placental stroma above the folded bilayer decreased with gestation and decreased more rapidly in placenta associated with the smallest compared with the largest fetus. These results indicate that the width of the microscopic folds of the placental trophoblast/endometrial epithelial bilayer is increased in placenta associated with small fetuses, which we hypothesize will increase the surface area for interaction between maternal and fetal blood supplies, thus improving placental efficiency in response to reduced placental size.

Authors+Show Affiliations

USDA, ARS, Roman L. Hruska US Meat Animal Research Center, Clay Center, NE 68933, USA. jeff.vallet@ars.usda.govNo affiliation info available

Pub Type(s)

Journal Article

Language

eng

PubMed ID

17709791

Citation

Vallet, J L., and B A. Freking. "Differences in Placental Structure During Gestation Associated With Large and Small Pig Fetuses." Journal of Animal Science, vol. 85, no. 12, 2007, pp. 3267-75.
Vallet JL, Freking BA. Differences in placental structure during gestation associated with large and small pig fetuses. J Anim Sci. 2007;85(12):3267-75.
Vallet, J. L., & Freking, B. A. (2007). Differences in placental structure during gestation associated with large and small pig fetuses. Journal of Animal Science, 85(12), 3267-75.
Vallet JL, Freking BA. Differences in Placental Structure During Gestation Associated With Large and Small Pig Fetuses. J Anim Sci. 2007;85(12):3267-75. PubMed PMID: 17709791.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Differences in placental structure during gestation associated with large and small pig fetuses. AU - Vallet,J L, AU - Freking,B A, Y1 - 2007/08/20/ PY - 2007/8/22/pubmed PY - 2007/12/28/medline PY - 2007/8/22/entrez SP - 3267 EP - 75 JF - Journal of animal science JO - J Anim Sci VL - 85 IS - 12 N2 - The efficiency of nutrient transport from the pregnant female pig to the developing fetus depends on the size and function of the placenta. It has been reported that maternal and fetal blood vessels are arranged in a cross-countercurrent arrangement within placental microscopic folds. Thus, the blood supplies are in close apposition to each other within these microscopic folds, and maternal and fetal blood flows in approximately opposite directions perpendicular to the plane of the placenta. This arrangement indicates that the width of the microscopic folds influences placental efficiency. The objective of this study was to determine whether differences in pig placental microscopic fold development are associated with differences in fetal size or are influenced by selection for ovulation rate or uterine capacity. Gilts from a randomly selected control line, a line selected for ovulation rate, and a line selected for uterine capacity were slaughtered, and uterine wall samples were collected within the placentas associated with the largest and smallest fetuses in each litter on d 45, 65, 85, and 105 of gestation. The uterine wall samples were processed for histology and analyzed using computer-assisted morphometry. Average width of the placental folds and average width of the placental stroma above the folds were measured. To measure fold complexity, the length of the epithelial bilayer for a given length of placenta was also measured. The width of the folded bilayer increased significantly from d 65 to 105 and was greater in placentas associated with small fetuses compared with large fetuses on d 105 of gestation. In contrast, the width of the placental stroma above the folded bilayer decreased with gestation and decreased more rapidly in placenta associated with the smallest compared with the largest fetus. These results indicate that the width of the microscopic folds of the placental trophoblast/endometrial epithelial bilayer is increased in placenta associated with small fetuses, which we hypothesize will increase the surface area for interaction between maternal and fetal blood supplies, thus improving placental efficiency in response to reduced placental size. SN - 1525-3163 UR - https://www.unboundmedicine.com/medline/citation/17709791/Differences_in_placental_structure_during_gestation_associated_with_large_and_small_pig_fetuses_ L2 - https://academic.oup.com/jas/article-lookup/doi/10.2527/jas.2007-0368 DB - PRIME DP - Unbound Medicine ER -