Placental accommodations for transport and metabolism during intra-uterine crowding in pigs

摘要: Litter size and birth weights are limited by uterine capacity, defined as the ability of uterus to maintain appropriate development some number conceptuses. Uterine capacity is result combined effects uterine, placental embryo/fetal function. The living conceptuses that capable supporting greater during early gestation compared later gestation. Plots log fetal weight versus also indicate less sensitive reduced (and therefore intrauterine space) in late However, even gestation, mechanisms still exist growth when placenta reduced. One such mechanism likely be improved folded placental-epithelial/maternal-epithelial bilayer. Fold depth, maternal interactive surface, increases advances from small fetuses. On side placenta, epithelial bilayer embedded stromal tissue. Glycosaminoglycans major components stroma, including hyaluronan heparan sulfate. Hyaluronidases heparanases present within tissues, play roles modification facilitate fold development. polymers forms glucose (glucosamine, glucuronic acid, iduronic acid) suggesting glycosaminoglycan synthesis may compete with needs developing fetus. Pig fructogenic, a substantial portion transferred mother fetus converted fructose. Fructose an intermediate product glucosamine glucose, linked regulation trophoblast cell proliferation through mTOR. These findings suggest link between fructose, synthesis, GAG production, morphogenesis, but details these interactions remain unclear. In addition, recent transcriptome analysis identified several amino lipid, vitamin, mineral hormone transporter placenta. Further elucidation morphogenesis solute transport could provide clues improving nutrient pig fetus, potentially increasing litter piglet weights.