Background: Embryo in vitro manipulations during early development are thought to increase mortality by altering the epigenetic regulation of some imprinted genes. Using a bovine interspecies model with a single nucleotide polymorphism, we assessed the imprinting status of the small nuclear ribonucleoprotein polypeptide N (SNRPN) gene in bovine embryos produced by artificial insemination (AI), in vitro culture (IVF) and somatic cell nuclear transfer (SCNT) and correlated allelic expression with the DNA methylation patterns of a differentially methylated region (DMR) located on the SNRPN promoter. Results: In the AI group, SNRPN maternal expression is silenced at day 17 and 40 of development and a third of the alleles analyzed are methylated in the DMR. In the IVF group, maternal transcripts were identified at day 17 but methylation levels were similar to the AI group. However, day-40 fetuses in the IVF group showed significantly less methylation when compared to the AI group and SNRPN expression was mostly paternal in all fetal tissues studied, except in placenta. Finally, the SCNT group presented severe loss of DMR methylation in both day-17 embryos and 40 fetuses and biallelic expression was observed in all stages and tissues analyzed. Conclusion: Together these results suggest that artificial reproductive techniques, such as prolonged in vitro culture and SCNT, lead to abnormal reprogramming of imprinting of SNRPN gene by altering methylation levels at this locus.

Fetal mummification is an uncommon condition in most domestic species. While most often seen in multiparous and polytocous species like swine, it is also observed in monotocous species when the fetus is retained for a long time. The low prevalence of the condition may help explain the scarcity of information in the literature. To further complicate the study of this phenomenon, the physiological mechanisms that maintain pregnancy vary between species, implying different pathways for the condition. The exact outcome of early fetal mortality is unpredictable, and is influenced by several factors, including the cause of fetal mortality, differences in pregnancy between species, stage of gestation at fetal death, and number of fetuses. Based on our current knowledge of natural fetal mummification events, there are a number of prerequisites for the process of fetal mummification to occur. Examining the circumstances associated with fetal mummification can help scientists better understand the etiology and clinical situation in different species. The objective of this article is to review fetal mummification in the major domestic species: cattle, goats, sheep, horses, swine, dogs, and cats. This paper discusses the clinical situation, the most common and important etiologies, and the treatment approaches for restoring future pregnancy in the female, and where applicable, herd fertility.