Altered placental lactogen and leptin expression in placentomes from bovine nuclear transfer pregnancies.

Appropriate growth, development, and function of the placenta is central to the success of nutrient partitioning between the mother, placenta, and fetus. Hormones such as placental lactogen (PL) and leptin are produced in the bovine placenta and play an important role in nutrient partitioning and regulation of placental and fetal growth. Nuclear transfer pregnancies are associated with a number of fetal and placental abnormalities, including increased placental growth and macrosomia, and hence represent a unique situation to gain insight into fetoplacental growth regulation.

Insulin-like growth factor-I and binding proteins 1, 2, and 3 in bovine nuclear transfer pregnancies.

In cloned pregnancies, placental deficiencies, including increased placentome size, reduced placentome number, and increased accumulation of allantoic fluid, have been associated with low cloning efficiency. To assess differences in paracrine and endocrine growth regulation in cloned versus normal bovine placentomes and pregnancies, we have examined the expression of insulin-like growth factor (IGF)-I and -II and their binding proteins (IGFBP)-1 through -3 in placentomes of artificially inseminated (AI), in vitro-produced (IVP), and nuclear transfer (NT) pregnancies at Days 50, 100, and 150 of gestation. Fetal, maternal, and binucleate cell counts in representative placentomes were performed on Days 50-150 of gestation in all three groups.

Cloned cattle fetuses with the same nuclear genetics are more variable than contemporary half-siblings resulting from artificial insemination and exhibit fetal and placental growth deregulation even in the first trimester.

The cloning of cattle by somatic cell nuclear transfer (NT) is associated with a high incidence of abnormal placentation, excessive fluid accumulation in the fetal sacs (hydrops syndrome), and fetal overgrowth. Fetal and placental development was investigated at Day 50, during placentome formation; at Day 100, when placentation was completed; and at Day 150, when the hydrops syndrome frequently develops. The NT fetuses were compared with contemporary half-siblings generated from in vitro-produced embryos or by artificial insemination (AI).