RESUMEN
Cloning procedures often interfere with conceptus growth and life ex utero, in a set of symptoms known as abnormal offspring syndrome (AOS). The aim of the present study was to compare the developmental pattern of in vivo-derived (IVD), IVF-derived and handmade cloning-derived (NT-HMC) Day 225 bovine concepti using established procedures. Pregnancy diagnosis was performed on Day 30 following blastocyst transfer on Day 7. Conceptus morphometry was assessed by ultrasonography on Day 51, and on Day 225 pregnant cows were killed for morphological examination of concepti. Pregnancy outcome was similar between groups, with greater pregnancy losses in the first trimester (70.6%) and smaller fetuses on Day 51 in the NT-HMC group than in the IVD (14.3%) and IVF (20.0%) groups. However, NT-HMC-derived concepti were twofold larger on Day 225 of gestation than controls. A higher frequency (63.5%) of placentomes larger than the largest in the IVD group was observed in the NT-HMC group, which may be relevant to placental function. Conceptus traits in the IVF group were similar to the IVD controls, with only slight changes in placentome types. Morphological changes in cloned concepti likely affected placental function and metabolism, disrupting the placental constraining mechanism on fetal growth in mid- to late pregnancy.
