Developmental and Degenerative Characterization of Porcine Parthenogenetic Fetuses during Early Pregnancy

Abstract

The difference between early pregnancy and delivery rate is quite large in assisted reproduction techniques (ARTs), including animal cloning. However, it is not clear why the implanted fetuses aborted after the early pregnancy stage. In the present study, we tried to evaluate the developmental and morphological characteristics of porcine parthenogenetically activated (PA) embryos or fetuses by electric stimulation during the early pregnancy period. The implanted PA and artificially inseminated (AI) embryos and fetuses were collected at day 26 and 35 after embryo transfer, respectively. The developmental and morphological parameters in the PA embryos at day 26 were similar to the AI embryos. The size, weight, formation of major organs, and apoptotic cells were not statistically different in both embryos at day 26. However, the PA fetuses at day 35 showed ceased fetal development and degenerated with abnormal morphologies in their organs. The day 35 PA fetuses showed significantly higher apoptotic cells and lower methylation status in three differentially methylated regions of the H19 gene compared to their comparators. Therefore, the normal development of PA embryos and fetuses during early gestation could lead to these pregnancies being misinterpreted as normal and become one of the main reasons for the gap between early pregnancy and delivery rate.

Physiologically relevant miRNAs in mammalian oocytes are rare and highly abundant

“…We microinjected fully grown porcine oocytes with the miR‐205 antagomir (~two‐fold excess over endogenous ssc‐miR‐205 molecules) and allowed them to undergo meiotic maturation, and then parthenogenetically activated their preimplantation development. We opted for parthenogenetic early development because porcine oocytes suffer a high incidence of polyspermy (Wang et al , 1994), while parthenogenotes can progress through the preimplantation development to the blastocyst stage (Hwang et al , 2020). As a negative control, we used let‐7a inhibitor as this miRNA is present but not effective in porcine oocytes (Kataruka et al , 2020).…”

Physiologically relevant miRNAs in mammalian oocytes are rare and highly abundant

“…We microinjected fully-grown porcine oocytes with the miR-205 antagomir (~2-fold excess over endogenous ssc-miR-205 molecules) and allowed them to undergo meiotic maturation, and then parthenogenetically activated their preimplantation development. We opted for parthenogenetic early development because porcine oocytes suffer a high incidence of polyspermy [48] while parthenogenotes can progress through the preimplantation development to the blastocyst stage [49]. As a negative control, we used let-7a inhibitor as this miRNA is present but not effective in porcine oocytes [21].…”

Adiponectin Improves In Vitro Development of Cloned Porcine Embryos by Reducing Endoplasmic Reticulum Stress and Apoptosis

“…In vitro embryo production by means of parthenogenetic activation, in vitro fertilization (IVF), and embryo culture techniques could be crucial for agricultural and biomedical purposes, as these biotechnologies could ensure good development and quality of embryos. Along with the success of IVF-IVC technologies, crucial improvements have been achieved in SCNT through the enhancement of enucleation methods, fusion, activation, and production efficiency [ 48 , 49 ]. However, embryos derived from current IVC systems still face the major challenge of low development rate and quality compared to in vivo-derived embryos [ 50 , 51 ].…”